Networking Notes

I'm Backkkkkkkkkkk!

2009-12-18T00:14:00.001-08:00

Hey common sense I'm back to write m two cents, I bet a lot of questions are going on about why would I start this blog and suddenly stop.

The ugly truth is I got bored of writing everything,
I feel as of a few days ago I will be explaining my Journey to my CCNA,
I will be getting this certification, if I like it or not!

I'm overly exhausted right now and will put up home schooled scheduled I will take any suggestions to make it better,

ICND1 Networking Summarization Cont'd

2008-11-18T18:42:00.000-08:00

A sudden burst of serenity, I believe life is but what you make it to be. We live in the millennium now, any thing is possible, creation is but at the tip of our fingers....

Now who do you know that dual screens with a blog on a 37" and dictionary on a 21" hmmmmm, well your reading his notes.

Now to stray from my digression and soak our heads back into the networking world, as I left off:

Ping is an important part of survival with a device, no answer to your request a diagnosis is required. We just about have every detail and step by step instructions on how to set any service on a machine. The real hard problem, getting it to work interactively with other machines. Imagine a group of people playing a friendly game of soccer, 5 to be exact, they are playing for 2 hours straight, and boom one of them hurt their leg and unable to join. Our soccer players are actually nice people that figure out that the only way to include their hurt friend is to play catch in a circle with the ball. Now that is how networking works, you add something new you use the machine to adapt to the new service or something is wrong with the machine you configure it to run the services. Some common mistakes when creating a universal deploy of any application, machines are not reaching each other this is caused by a interference between a machine(shutdown of machine, user logged off), or another machine doing its job that won't let you do yours. A little advice when handling new installations setups or whatever... know your network and know it well.

I will be attacking the Datalink Layer:

Another hard part to the puzzle of connection, MAC address its a 48 bit 6 byte mac address that has precedence within our networking worlds. MAC is derived from Ethernet, Ethernet is the standard low bit encapsulation package that has become the renown in the world of networking, screw token ring.

Why so important MAC, MAC is burned into your network card, each MAC address contains specifics of your NIC, part of your MAC is learned by our lovely powerful devices called switches, there for in order to understand a switch clearly you must understand MAC.

Starting from the inside out, I would like to yet again to imagine a picture that I have been looking at for the last 2 years, one that should be so familiar to you that every time it is mentioned you should gasp in AH!! meaning you do understand.

4 PCS attached to 1 SWITCH

SWITCH
------------|-----------
| | | |
PC1 PC2 PC3 PC4

Each connected to a switch port, what do you know about a SWITCH, each RJ-45 has a separate collision domain, the other half of the DataLink Layer is deciphered as the LLC layer, this layer tells the PC when passing the packet to the physical layer what lucky protocol will get the job in delivering the packet.

Stick with me here this is important, and I'm not showing you any history to learn, I'm showing modern day logic and fact.

Each PC is on a separate line and because each have a separate collision domain no interference (internal) will occur. Embedded within MAC/LLC is CSMA/CD stands for the acts exactly has it sounds

Carrier : Signal
Sense : Detect
Multiple : Equals Access
Collision : Two devices at one
Detections: How to handle the collision

to send the signal containing the 1's and 0's to the switch for it to be compiled and understood and sent to the right interpreter to be received.

Damn how I've strayed away from my original question...if you don't remember.... Why do we need MAC.

Well we'll get their real soon, as for signals a device can send out their are three

UNICAST - 1 to 1
Multicast - 1 to many
Broadcast - 1 to every 1

to send to multiple clients servers whatever you may be doing within your network, the whole point of this is that MAC traces your PC in a table in order to identify where you are in the network, no not to spy on you, but make it easier for the other users to send stuff to your PC. MAC addresses are stored in ARP, ARP is backward compatible with IP and make a great datalink layer protocol in order to send data fast to the recipient.

And to be VERY clear on it ARP saves time, MAC is saved within your NICS arp table and MAC is saved in the CAMTable within switch's this creates the switch to become intelligent and your PC to be even more intelligent.

This function of ARP is called gratuitous ARP sending a broadcast (0xFFFFFFFFFFFF)to let know every machine on its segment that is connected. Most likely notified the router. ARP(0x0806) is encapsulated in the Ethernet Frame.

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As I can ramble on about the ARP protocol for years I think this is sufficient enough post to have you up to par with the common ground of networking....boy is their alot more to come.......

---All we have is time

ICND1 Networking Summarization

2008-11-15T16:52:00.000-08:00

The studying for my ICND1 has been doing rather well, due to some minor set backs from the last week I should be done all my ICND1 videos for my CCNET certification. This blog entry will summarize all 14 videos I have viewed. In the course that I have skipped any critical information I will be using my notes and this entry as a reference when re-viewing the videos before the exam.

Brace yourself here is what I've got out of 14 videos:

The common question that anyone should ask a network engineer is WHAT IS A NETWORK?

Now before reading on please ask yourself the question and consider.

Okay since you have the answer I will share what I have come up with:

Through civilization we have always strive to come together, build as one, and most of the trying actually got done. Sometimes what got done was by force by now is usually compensated with mula the bucks. As I vision it like we use cement to build roads and highways, we use wire(copper. coaxial, (air)frequencies) to build roads for information sharing. When we share information before computing we used the post office, and Networking is similar as sending a letter in the mail, the envelope(packet) gets tossed(transmitted) in a bin(NIC card) then carried to the post office(wire) where it's sorted out (digital device like a router) and sent to the right destination, and sometimes it must hit multiple destinations before it arrives.

So for a more simple answer a Network is the fabric that ties, through multiple digital devices, information to reach its destination.

Some key attributes in networking:

Switch - Central meeting place for all packets, has separate collision domains

Router - Relays information to the WAN (Internet)

Internet - Multiple routers connected together

WAN - fast link ---AT&T

In order to use a network efficiently companies and people have needs in order for them to co-operate and operated effectively in today's modern fast changing world. The dire commonality is the communication between services within high end servers. Like human's computers now have a set a tools that have a commonality with standards which are called ports.

Some well known PORT numbers:
TCP UDP
21 -FTP
22 -SSH
23 -Telnet -69 TFTP
25 -SMTP
53 -DNS -53
80 -HTTP
110 - POP3
443 -HTTPS

Each port has its funcation which should be already be known at this stage of the game by the reader, due to the practice of hard school work.

In order to test things are working properly and things are 'alive' as I like to call it, a ping request is sent to the ports, alive will signal back !!!!!!!.

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Yes it has to end now I seem to have gone into a mind flux which needs a bit of entertainment.

Stay tuned to next post it will be more dynamic and lengthier.

I'm back

2008-11-01T13:12:00.000-07:00

It's been almost 5 months (1 more day) since I have posted any information, yeeshhh, It could be either I've been lazy.....no that's not it, I've been ever so BUSY!

Well its good to be back on the blog, I decided I'm going to keep this as a journal of information gathering, even though it seems to be I am going to be a little bit more interactive (of course with myself) rather then just place information on the page.

I haven't thought of what the rubric of the flow of information should be, but I will soon gather all my neurons and conjure up something.

Since I was gone....anything new......well I'm going to go get my ICND1 by the end of Nov, So I will be studying hardcore and updates of information will naturally flow onto the site. I have also been in co-op working in the information world, knowledge society as I see it. I will keep my views of the environment to my personal journals due to the public status of this blog. Oh and if it hasn't caught your attention yet, my implicit and explicit memory skills have gotten better 10 fold even my writing has more spunk to it!

Experience does matter, I believe its the whole visual aspect that teaches the student.

Till next post,

Frank

SEC703 1st Lecture

2008-07-02T21:13:00.001-07:00

Core Distribution and Access Layers

Router , Firewall, DMZ then another firewall,

The first router does basic access control lists,

Standard things to block, telnet traffic, secure shell traffic except for specific devices, at the router level

then the Firewall gets specific,

Then DMZ, any devices that needs to be accessed from the internet, web servers, databases (sales), the web server access the database server,

you put ur e-mail transfer agent, then the transfer goes inside,

A DNS here at DMZ, broadcasting the name resolution on the dmz, receiving info from the inter organization,

Look by name instead of ip, nothing transferred out, another firewall in DMZ

realistically another firewalls to the entrance to the data center

Separate them through blades, firewall blade, diff ports for different functions,

VPN blade terminates inside the firewall, VPN access secure encrypted tunnel between point A and B

-adds a second address header, it will have ENCRYPTED[Application Presentation Session Transport network ]Network Data link and physical

IDS -specific blade, specific traffic at all times, shows you whats going on, you must write the list and implement it

IPS - write information to block new traffic , does it auto magically.

Honeypots, put in DMZ to attract hackers,

-------------------------

Traffic shaping aka QoS guardsmen throughput, throttle back specific types of traffic, organizations you this all the time,

Mission critical and non mission critical data, if info is going slow theirs something wrong,

Info that music flow, Voice and Video, priority

Internet Proxy - (Specific HTTP and HTTPS traffic) Single device buffering and monitoring device, everyone goes through the proxy, all HTTP HTTPD traffic, through the firewall is the proxy device, it will collect the info and send into you, 1 line in the ACL, you can put web monitoring tools into the proxy, block stuff

Networking Devices - talking about controlling traffic

Mitnick - Communications Technology

2008-06-27T21:12:00.001-07:00

Mail Drop - The Social engineer's term a rental mailbox, typically rented under an assumed name which is used to deliver documents or packages the victim has been duped into sending.

Data Classification Policy - the differentiation of securing public and private information

Innocuous - not harmful or injurious, harmless

Information Security Department - ISD
Conducts:
-awareness training
-detail methods

Explanation: Social Engineer Employees

-Lingo| "Use None Sensitive things" [Poker Chip]

Types of Security Violations

2008-06-27T11:20:00.000-07:00

Here are some basic component violation in security, in the perspective of the malicious code,

Virus :Typical piece of code copies itself into a program, and executes when the program runs

-modifys other programs
-loss or contamination of data, or program

Worm: Reproduces itself until slowd down or shuts down a comptuer system or network, does not notify other programs

Clogging or Flodding : Form of a worm
- sending large amounts of bogus traffic too a node until clogged and unable to serve a legitamate user. AKA DoS Attack (Denial of Service)

Trojan Horse : piece of code, hides itself in another piece of a program

"Think" a simple login screen
Login Code
Hidden Code <--------interlopes exits with no trace (steals info)
Login Code

BOMB: Same as a Trojan
signature" time or logic trigger

Trigger software routine, upon detecting the absence of the rogue program records, initiats actions to damage the system

Trap Door: Allows penetration into the system can be programmed in code by programmer. Usually used in case you must get back into the program to fix something. Usually guarded by authentication process.

Salami: Small alteration of numbers in files having of numbers and distorting the system.

Replay violation: Active attack on a resource.
entails: capturing data, perhaps modifying and resending it.

John Searle, The Chinese Room

2008-06-23T10:05:00.000-07:00

Philosophy professor at Berkeley, On Intelligence

The Chinese Room:

Suppose you have a room with a slot in one wall, and inside is an English-speaking person sitting at a desk, He has a big book of instructions and all the pencils and scratch paper he could ever need. Flipping through the book, he sees that the instructions, written in English, dictate ways to manipulate, sort and compare Chinese characters. Mind you, the directions say nothing about the meanings of the Chinese characters; they only deal with how the characters are to be copied, erased reordered, transcribed and so forth.

Someone outside the room slips a piece of paper through the slot. On it is written a story and questions about the story, all in Chinese. The man inside doesn't speak or read a word of Chinese, but he picks up the paper and goes to work with the rulebook. He toils and toils, rotely following instructions in the book. At the times the instructions tell him tow rite characters on scrap paper, and at the other times to move and erase characters. Applying rule after rule, writing and erasing characters, the man works until the book's instructions tell him he is done. When he is finished at last he has written a new page of characters, which unbeknownst to him are the answers to the questions. The book tells him to pass his paper back through the slot. He does it, and wonders what this whole tedious exercise has been about.

Outside, a Chinese speaker reads the page. The answers are all correct, she notes--even insightful. If she is asked whether those answers came from an intelligent mind that had understood the story, she will definitely say yes. But can she be right? Who understood the story? It wasn't the fellow inside, certainly; he is ignorant of Chinese and has no idea what the story was about. It wasn't the book, which is just, well, a book, sitting inertly on the writing desk amid piles of paper. So where did the understanding occur? Searle's answer is that no understanding did occur; it was just an bunch of mindless page flipping and pencil scratching. And now the bait-and-switch: the Chinese Room is exactly analogous to a digital computer. The person is the CPU, mindlessly executing instructions, the book is the software program feeding instructions to the CPU, and the scratch paper is the memory. Thus, no matter how cleverly a computer is designed to simulate intelligence by producing the same behavior as a human, it has no understanding and it is not intelligent. (Searle made it clear he didn't know what intelligence is; he was only saying that whatever it is, computers don't have it)

--Jeff Hawkins, On Intelligence

SEC520: 10 More

2008-06-14T11:18:00.002-07:00

Here are 10 more Security Log Management at both the Infrastructure and System Levels

Log parsing: using log data to be used as another part of the logging process

Event filtering: suppress data that is not needed like the duplication of a record.

Event Aggregation: Logging same events as one and counting each occurrence.
Log rotation: rotate logs to make them manageable, ex: examine archived logs to perform filtering.

Log archival: keeping logs for a extended period of time on a SAN’s network, two types Log retention archive on a regular basis, or Log preservation, keeping logs that would be discarded because they contain records of activity of particular interest.
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Log compression: reduce the amount of storage space needed (filter)

Log reduction: remove entries of no important to make the log smaller

Log conversion: convert logs to different formats XML or database

Log Normalization: Ordered in a particular data representation and categorized consistently. DATES and TIME in a single format

Log file integrity checking - having a message digest for each file MD5 or SHA1
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Event correlation: finding relationships between one or more entries

Log viewing :Display log entries in human readable format

Log reporting: displays the results of log analysis
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Log clearing: removing all entries from the log that precede certain date and time. Remove old logged data b/c importance has been archived.
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Syslog is a central framework for log entry generation, storage and transfer, the syslog format assigns messages based on importance. Two attributes to consider are message type, known as a facility(kernel messages, mail system messages, authorization messages, printer messages, and audit messages). Severity a value assigned, from 0(emergency) to 7 debug.
Mar 1 06:25:43 server1 sshd[23170]: Accepted publickey for server2 from 172.30.128.115 port 21011 ssh2
Mar 1 07:16:42 server1 sshd[9326]: Accepted password for murugiah from 10.20.30.108 port 1070 ssh2
Mar 1 07:16:53 server1 sshd[22938]: reverse mapping checking getaddrinfo for ip10.165.nist.gov failed - POSSIBLE BREAKIN ATTEMPT!
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Syslog security does not conform to the use of basic security controls that would give it the confidentiality, integrity and availability of logs. Weaknesses the syslog protocol encounters is the UDP transfer of data, anyone can send information to the syslog server(DOS ATTACKS). MITM on the syslog, and analyze the syslog for a vector.
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Reliable Log Delivery, TCP
Transmission Confidentiality Protection, SSH TLS
Transmission Integrity Protection and Authentication,MD5 SHA-1
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Robust Filtering –handles messages based on programs or hosts that generate a message or RE matching content in the body.

Log Analysis –Use separate add on programs to analysis data

Event Response – Alert admins through pages or e-mails

Database storage logs, log file encryption,

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Security Information and Event Management Software that is a centralized loggin software , SEIM does its job
Agentless which would mean it pulls logs from the hosts by authenticating to each host and retrieving logs, or the host pushing log files on the server this server will then perform even filtering and aggregation and log normalization and analysis on the collected logs

Advantage no installation on hosts, Disadvantage – large amounts of data transferred, some need credentials so you have to install an agent on the host.

Agent-Based all the filtering and aggregation and log normalization is done at the host then transmitted

Advantage all filtering and aggregation don’t on the host, small load going over the network , Disadvantage – installing agents on every host

SEC520: Whizzing About - Senecan

2008-06-12T21:04:00.000-07:00

Since I've been to busy \n I haven't been posting ANYTHING OH NO! \t Well I decided I'm just going to go on a snippet| \ spree->(enjoy) since this semester has taught me well...these condensed courses have put me in the mind_frame of shaving the bits off everything and putting it to light,_\ I'm going to share my mini definitions.

10 - Question Answers SEC520:

Services such as firewalls, routers, authentication servers, and intrusion detection and intrusion prevention systems provide logs useful information for security purposes.

\System Events – ex: LDAP/Kerberos authentication response for services, error codes, user accounts and systems account with an event are logged and checked for any suspicious activity.

Audit Records – pertain to more administratively tasks that are generated and logged, ex: security policy changes, policy folders/file access, account changes

Client request and server responses are logged in order to check on persons transactions between systems when accessing/ using certain resources or networked resources ex: E-mail, web browsers,, business applications.

Account Information: checks the failed authentication attempts, account changes, and use of privileges. This also identifies any malicious attacks toward the account and the use of what applications used by the client.

Usage information: checks the number of transactions occurred in the case that any malware threat or anything abnormal in size might indicate suspicious activity such as the transfer of company internal information.

Significant operational actions: checks application startup and shutdowns, application failures and major application configurations changes

Log management is necessary to provide sufficient detail of processes for an appropriate period of time. This will enable revision of logs in order to identify any security incidents, policy violations, fraudulent activity, and operational problems shortly after the initial occurrence.

Log Generation: Hosts generate log data; they are retrieved by logging client applications, services that are automated retrieving processes either by authentication or networked log servers.

Log Analysis and Storage: Receive the log data from the hosts that are gathered in real-time, near-real-time, or batches the servers are often called collectors or aggregator's. (Multiple: 1 analysis, 1 storage)

Log Monitoring: Analysis of the data and generation of automated reports.

SEC520W2L2

2008-05-26T20:10:00.000-07:00

PAM Today

AAA Friday,

Next week hardening Linux, he will rejig Lab5 and Lab5b

Tuesday next week is a lab day

He moved the test from this week to the 27 till the end of week3 the test is up to

ChaPTER 5 and the intrusion discovery, n Hardening Linux

Put off the take home tank lab,

Finish up to lab 4 by Friday,

When he says its due, he is going to take the open boodle, PDF file report and upload it to open

And He will mark it online, and you must upload it by the due date

NO distatory recovery,

Test is on exploits and the text the stuff we do on labs,

PAM a lot of the labs are about

This week Access Control,

Linux comes with a lot of services working independently,

Till Pam came alone in the terms of Authorization and Authentication you would have to do everything independly

PAM is basically a system you can set all the authentication parameters through one program and have it affect all the services,

Theirs a directory PAM.d their use to be PAM.conf one file with the services, PAM is the same as xinet.d what ever you want to control with pam you put the config in the directory theirs another file called other and is the default that will handle the services, it comes in modules. Modules use permission and passwords,

Is the password strong enough, you can determine is the auth is going to fail or a warning you might say they have a weak password and go in or password weak you cannot go through you can do this all through PAM,

If you look at pam it carriers a lot of files and you can also see all the services that have configuration files, the default is other,

Looking at the files we can see …the login one… we can see four interface types, theirs AUTH this is called stacking modules, the login process uses 11 modules, and each modules everyone uses login the modules are executed one at a time, the first thing is authentication auth , after that required means this must succeed or the login field, more then 4 required mean both requisite means this this failed then the login failsso if 4 fail it will fail in the end, if it says requisite it will stop.

Option will give a warning,

Sufficient that means if there are all sufficient then some will pass,

So you have interface the parameter how it will work then the module, to find out how they work you gotta do research on the module, some commonly and some aren’t

System.auth is used often, after the module theirs parameters that are sent to the module

You can find out on the net how these works, if you look at the links on the course notes you can look at everything and see what it says,

Going through the lab do backup reading and see what it does, no ignorance!

We will look at password checking and setting criteria for authentication for the needs at the time, we are looking at the basic of using one thing you always do , is so ssh does not allow root login, people will try to brute force password for root login, never login as root through ssh or login as all if exposed to the net ,

Pam solves the previous problem.

The stream to crytography

2008-05-25T21:53:00.002-07:00

One-TimePad
Cryptography
Kerberos Protocol

The stream to crytography

2008-05-25T21:53:00.001-07:00

SEC520 Types To Regard As Security Personnel

2008-05-21T20:56:00.001-07:00

You always need to access something pretend you want to print you must switch to partial system administration your software uses the network, its controlled but parts are making use of kernel states that have admin control,

Hackers will break the software right when that’s happening if they do that they can break the shell and have access control of the tat process, and that’s one of escalating privileges and that’s where the loop holes are, its like the cgi programs, it does things that a user cannot do that an escalation of privileges, implementing is really hard because its so hard its always going to flawed the trick is not to have it prefect but now be the low hanging side , the bigger the value of the prize the more stringent you have to be, if they can make 10million they will spend 1 mil,

You come up with policy rationale three things to think of ,

One thing is

1. Due Diligence – your legal obligations, protect it

2. Risk Analysis – Cost of Benefit “How much will it cost and how much am I going to lose” Intelligent guessing

3. Exceed the Standards - Why? Bear chase phenomenon if you in a party of campers you try to be faster then the other people,

History:

In the beginning of computers, their were no passwords wasent an issue originally first computers were batch operators, they do one job at a time, so a computer center, it would be in a basement where the banks of memory the size of a huge cabnit and you would do your punch card, so one job at a time controlled by an operator, one job at a time you couldn’t cross boundaries, “think” MIT came up with the concept of time sharing that not all process is busy all the time, theirs I/O, its split into chunks and they all had a dumb terminal, except for a big centralized machine, what happen that some people were getting access to things they weren’t suppose to, and some errors and data would overwrite because their were not access control stuff, because in the early days they didn’t know so they came with access and password, they didn’t like the idea the machine control what they could do, suddenly the system would dictate to them and was a huge loss of freedom, Richard Stallman, Their was quite a resisted against password, then they broke into the password file and tried to live in access one famous incident, one was setting the login procedure and he look at the login and a password file would come up.

Someone would have a password file like the /etc/passwd in linux when you login program must have access to the file to see if ur their it use to be user name and password what they came up with is a
one way hash(cryptography technique) user puts into a password and given to a hashing algorithm MD5, if you give this the same input it will come out with the same output, so they store the hash of the pass except the password itself whats stored is not the same what is put in,
2 characteristics

1. It cannot be reversed,
if I have this I cant figure out this,

2. Given input always produces same output,
2a. any change to input how ever small produces completely different output

If I change 1 letter the output will be completely different,

Have a good logging system, everything being keyed were being cached in the buffer and waiting to be given to the hash,

Other thing realize in login you shouldn’t log password, which means also logging user names with failed attempts

You want to store them from successful ones, you want ot know who they were and where they came from, something simple become complex,

You remember the CIA if you kick ur users off the system cause their making mistakes you are failing accessibility, once they solved that stuff, what’s the weakest link, the first element the employee, social engineering, they will use passwords that are easy, or they can use social engineering, have educations and user friendly policy easy to understand and educate the user why the policy is important, you can do this well, sec625 is human side of the security,

Issue of sniffing,

Don’t use telnet use ssh, make sure you have ssl happening, any password in the wire should be encrypted before going in the wire

ShoulderSurfing, someone watching u type,
They can be grayed the Astrix

Other types of sniffing, one of the links, think geek, it’s a key sniffer, if going on a pc keyboard it’s a key logger,

Monitor Radiation, Vantek, if you invest something monitoring e

Key board timing attacks – you can decrypt them

Cost benefit analysis

The Trojan login, thinking when you login you see a prompt user name and password, its not hard to duplicate that, here what you can do if you have access, you leave th screen on so write a program so ur program runs inside of the login then you present a error then it passes it to the system,

Ettercap, is an evil program, it makes it easy for man in the middle attacks insert urself in the browser and server, it makes arp poisoning easy, knowing this if your on a lan with strangers you should not do anything that private,

Authentication factors, three factors of authentication,
1. Something you know the most common example is a password
2. Something you have – token key
3. Something you are – bio metrics

First password, they are easy to implement , no need to buy hardware or software, weakness choose weak password, we all know this,

Strangth if someone has it,

Weakness it can be forgotten come to work without ur token you cannot login, stolen, required extra hardware, you have to install a token reader on every machine, if you use a special card or device it can be expensive

4. Bio-metrics – easy to fool, you cant get 100% of the percent the higher percent the more it costs, if I gets easy if can interfere with it you need a huge database something the gnarl public is using it needs a huge database, if you their checking ur finger at the boarder what kinda pipe line would you need, so yo need to think about things like this they can take photos of your eyes,

ATM strategy

2008-05-21T20:55:00.001-07:00

Well in today’s world everything is moving fast we are all learning and re-learning new things over and over. Before I start I wanted to ask the class why do they think emerging communication technologies are here? Basically why do we need to communicate them?

Well Uyless Black, a lecturer on communications technologies says

Today emerging technologies are here to overcome the deficiencies of the current technologies. Each new technology must meet the needs of applications

What he’s basically saying is we don’t need faster computers, we don’t need faster applications WE HAVE THEM and they are advancing in a millisecond rate, we need better communications between systems to be more accurate between Wide and Local area networks.

We choose Asynchronous Transfer Mode not because it’s a any protocol it’s the mother of all protocols and you will learn why in just a few minutes.

Just to define some how some of the information is handled before it actually transmits data, PMD synchronizes the transmission and reception of the connection and maintains continuous flow and TC allows devices to locate cells within a stream of bits.

Now I know what you guys are all thinking, How then this information directed…well first in front of the information you want to send there is header which contains all specifications about the load that will come after it, this is similar to an envelope, What do you need for an envelop? A Stamp, Mail Address and an optional Return address, you might even need two stamps!

So when your first going to send out your letter you put the right information on the top then drop it off to the closest mail box, after the header there is the pay load and we can see this similar to the mail carrier that carriers all ur letters and delivers them to the right destination, and like your envelope when they reach their destination the Name on the envelope is the person you want to be reading your message. That is similar to what the payload incorporates.

Now your thinking I got the envelop I wrote the letter but then who’s going to carrier my letter to my friend! Well actually you don’t care, but for ATM and as a Technician you must know which device you’re going to hook up

You basically use Switches/Bridges, they are two devices but are usually now embedded into one and perform functions what is inside the header and payload. Now we know how its directed and how its carried, now how is it handled?

Well inside each header there are bits called the VC and VP each of these are similar to telephone numbers but only regarded to each switch/bridge/router locally and no significance when transmitted except during the process of the switch where it translates that number to the right path in the opposing network.

INT525 Compile Process

2008-05-18T22:23:00.001-07:00

Just some stuff I've been working on.....you know this one actually is good instructions.....Apache Installation

Creating symbolic links to start up Apache, S__ and K__ in init

We download the source tarbal

Untar it with tar –xzvf

Make sure no one can log in if you do this to their account /bin/false

7 fields per user etc passwd

Everydeamon /bin/false

When installing we user

Do not do this as root,

Make
Make test

Make a dedicated directory to deal with your source code

/exp/src

Your configuration needs,

Document Root
Server Root
Extract Binaries
Change Executable Directory
Configuration Files

All command line switches, and easier more quickly with config.layout

# SuSE 6.x layout

prefix: /usr
exec_prefix: ${prefix}
bindir: ${prefix}/bin
sbindir: ${prefix}/sbin
libdir: ${prefix}/lib
libexecdir: ${prefix}/lib/apr
mandir: ${prefix}/share/man
sysconfdir: /etc/httpd
datadir: /usr/local/httpd
installbuilddir: ${datadir}/build
includedir: ${prefix}/include/apr
localstatedir: /var/lib/httpd
runtimedir: /var/run

Buildconf (first time system inspection and change system tree appropriately)
./configure (command line switches –withlayout)
Make
Make Test
Make Install (Don’t Do)
Make Clean

We are done unless we want to statically compile some modules, modify the build dso capabilities, we must compile the mod_so

Run shell script to automate this and make modifications to it and run it

INT525W2L2

2008-05-13T18:18:00.000-07:00

Modules you can add them dynamically or statically

Statically – part of the binary

Mod.so is required if you want the rest of the modules linked dynamically,

Dso vs Static

Mod.speling in the url simple module that makes you make one typographic submission in the resource you are going, cgi-bin without the - that will be an error mod.spelling will correct.

Mod.alias, gives you ability to alias directory,

Script.alias, like alias with executable power, don’t use it, does not give you the control of flexibility alias does with a directory container,

Talk about basic directive in apache we know, and some modules that supply them,

When you come to a website you are virtually hosting, the main thing that must be set, you have a principal one that you might call default or main,

If you ask for a IP it doesn’t know or a Name VH they don’t know, they have to have a default way for the request, one of the metrics it must be rebout and must be forgiving for arrant behaviour a forgiving behaviour

When it does not know the deafualt behaviour will give to the main server,

WE need to learn the simple procedure this is the default place to go and you come in for a name server, this is the place to go if we are not servicing that IP,

What things need to go into the virtual host container for the main or default server

ServerRoot parent of the apache binary trees,

LockFile /var/log/apache2/accept.lock

IfModule directive all supplied by modules, nested tree of a fork, the later one will hold true, the last declaration has more authority, precedence

Which one has higher precedence, the example is not particularly authoritative but they actually fork the decision tree, not at run time, the service is running, we are either going to go around it or go through it

So binary executable for the binary,

.c static linked component of the kernel,

This says IfModule, if you move the config to a machine and you recompile it wont blow simply trying to start so it will not do these things

This is the global configuration file httpd.conf

Reaps the child processes,

MaxSpare initiates repeaing responses,

MaxClients = Maximum requests

Worker.c

443 ssl’

Directory < “/export/srv/www/vhosts/main/htdocs”>

Main => ALL FQDN
Perl

AllowOverride None

Worker.c
A typical configuration of the process-thread controls in the worker MPM could look as follows:
ServerLimit 16
StartServers 2
MaxClients 150
MinSpareThreads 25
MaxSpareThreads 75
ThreadsPerChild 25

Server limit identifies what will initially launch when the server is started it must be greater or equal MaxClients / ThreadsPerChild

MinSpareThreads and MaxSpareThreads identify the the idle threads in all processes and forks or kills processes to keep this number within the declaration

MaxClients the maximum total number of threads in all processes.

MaxClients / ThreadsPerChild = Max Child Processes

150 / 25 = 6

ThreadLimit must be greater or equal to ThreadsPerChild

While the processes are started as root under Unix intorder to bind processes and threads binding them to port 80 Apache will use less-privileged users.

#
# If you wish httpd to run as a different user or group, you must run
# httpd as root initially and it will switch.
#
# User/Group: The name (or #number) of the user/group to run httpd as.
# It is usually good practice to create a dedicated user and group for
# running httpd, as with most system services.
#
User daemon
Group daemon

MaxRequestsPerChild controls how frequently the server recycles processes by killing old ones and launching new ones.
Description:Multi-Processing Module implementing a hybrid multi-threaded multi-process web server
worker.c
it retains much of the stability of a process-based server by keeping multiple processes available, each with many threads.
Or
Prefork.c
It is also the best MPM for isolating each request, so that a problem with a single request will not affect any other.
Directive and Declorations

Declarations = Server Name

Directive = alias this directory their

Directive that configure this to the relation to mother child

\

ONE PARENT

worker.c has a different parent the child process then prefork.c
worker.c uses ThreadsPerChild that controls the number of threads deployed by each child prcess and Max Clients right
while prefork.c uses MinServer and MaxServer that spawns childprocesses that are indepent from the kernel
threads works as a stream as prefork words as a dependent entity

First thing that your going run out of when your worker.c is cpu and prefork.c is memory

Remember to check
http://httpd.apache.org/docs/2.2/mod/prefork.html
http://httpd.apache.org/docs/2.2/mod/worker.html

SEC520W2L1

2008-05-13T17:19:00.000-07:00

Exploits - things that can go wrong

5 years script kiddies, now its criminal activity and has really changed, over the next few
Years it’s going to change again.

The change from operating attacks to application attacks, when you have applicatios you have a lot more variables then with dealing with the os many more applications and all doing different things, OS are straight forward applicationts are dynamic.

You still have the same things the attackers will do,

What is a DoS

CIA

Confidentiality,

Keep it secret

Integrity

Information from the data is what it should be, for instance you look at your bank account and you want to know the numbers are really their.

What it should be when it should be.

Lot of do who changed it who can change it.

Identity how do you prove someone is who they are.

Accessibility

Avaliable when its needed in a timely fashion.

DoS denies accessibility

DDoS – Distributed Denial of service

One way is to break the software this is one way another common one its not through breaking the software but overloading or clogging the piped to it.

Thisi is where DDoS, BogNets one central system which controls many computers so no one can access the service

DoS the basic, it has been mostly preformed for kids in basements or unhappy employees, They have been used for extortion, if you shut down your site it can cost you 30000 dollars it can be a real problem and it has in some palces ,

Why is the web to vulnerable to risk,

When it first came out everything was open and a kind of utopian world,

John Morris, the son of a internet pioneer the son wrote a program to find how mayn users are on the internet, thousands of the them, it used the finger deamon and it would move itself on the machine and do finger searches, he forgot to do make it see if its their, it was a naïve thing, he wrote a program that invaded other peoples computers,

Firewalls – controls what gets in and out, a firewall originally, first basic fire wall did packet filtering, looks at each packet and looks at the ports what ports is it asking for suppose you have telnet inside which is port23 and you have ssh 22 and http 80 and so , suppose you want telnet internally but not externally lets say it gets stop at the fire wall if you wna the public to have access to your web server then you make them go through that only port, may port for 25 but you restrict it to the ports you want to get through,

What happened when it was in place, everyone started having a webserver, webservers would give you some documents, well the people that wrote webservers what if it can expand to dynamic content or video they made more expansive webserver and create dynamic content.

Dynamic more accessible to the public, then they explanded the firewall they had web services goes through mysql, and come up more complex and they have holes to powerful complex software, the attacks change what they do and start aiming at the dynamic attributes of the server not just HTTP, but HTTP are common cause they do so many things and because theya re complex they are perfect targets for running exploits the exploits have gotten more and more toward webbrowsers.

Embed macros, it’s a program in a program web applications become a good target

Email targets are great bc of spam

Media players complexity, YouTube.com vector to get into the system passed the firewall.

On the server side service os the OS security software becomes a target for attackers, get a couruppted version. File management servers and database software.

Also things aimed at people, user rights unauthed devices,

Phishing, your account is over due give ur password, got all the right graphics but its false,

Spear phishing when you target people, or you lap top of usb keys, wireless if a grate vector

Instant messaging, easy for all the dumbasses.

Zero Day Attack, an attack where the attackers know it can mount it before the vendors know its their, it usually happens with hacks someone finds the weakness posts it then it the software vendors will patch it.

Because we have sophisticated criminals before they use

Storm Worm,

Recognize trends

Talking about DoS

Another privileged escalation – its like a user getting root access, some users on a a system but you want to get higher.

Trying to get from out in the cloud through a couple of a server, if they see outside traffic doing into system they have logs or IDS, they can call your service, or police come knocking

They will break in further away to get closer to the machine, trying to get machines to do the work for them, this is slow so they can get privileged escalation.

Common things, two things you will see a lot of,

XSS - Cross Site Scripting

SQL Injection

Everyone is blogging, websites allow users to put stuff in, cross site scripting when you put data in a blog that will effect the behaviour of a server, thing about it like this someone goes to a site, and look at someone’s blog the big thing now is java script, Java script embeds some code in your webpage, when the browser gets the webpage it runs that code, it allows the code to run on the clients machine however evil stuff can get in it, in cross site scription when you look at a wikipage or a blog, that will not be visible by you that will be executed by ur browser.

A lot of sites and wikis check this, but if its sophisticated it will always get through,

SQL injection when a web server is sending queires to a database databases by nature have a lot of data, its in a hackers intrest to get access to this.

If you design ur self right you, you use –T cause if you web server is interactions with database server if someone slips some sql code in the stuff that gets stuff into the data server can do bad things, get access, integrity, unauthorized, find credit card numbers.

DNS poisoning put false entries, collecting data,

Identity theft,

New devices for password, MLS and email password for only 30 seconds

Assignment 1

WHOIS
GOOGLE
DNS Tools

CanadianISP.com

Take it a generate a report a .pdf file and you can upload it

First Weeks Early Insight

2008-05-08T16:20:00.000-07:00

From the lack of communications you can get between parties and individuals I find it a great way to express my feelings toward a culture that is so dynamic.

Well the first week is almost done, the new semester courses have focused themselves into a security mold. When exploring each subject we delve into the issues of a structured implementation of a dynamic model. A model consists of mainly the preface of a system and its inherited risk to exploitation. As computer administrators/networkers our jobs are to keep it secure and readily established policy that will protect all resources.

What I Learned This Week:

Nothing is impenetrable, we must see that anything so and anywhere especially in corporations faults are lurking in every corner. In order to minimize any risk associated to hacking or information gathering we must see the risks before planning the structure of any aspect. Consulting security process steps we bring down the risk of being penetrated and taken advantage of. I am looking forward in continuing the penetration process with an attackers mind as well as a defender. FIRST THE ATTACKER! :)

Other then the topic of security....WIN700 the last bit was about INT525/SEC529...Win like security is structured in a way you must be privileged in order to acquire any administration rights. The overall implementation of the Active Directory structure is driven by the associated objects to point active users and computers to the the granted applications or services that they use in their daily functions in what ever department they me be in. The structure of Forests and Trees build up relationships between each other called Trust relations ships as well as cross trust. Different versions or you can say more correctly Function Levels Domains/Forest also implement many features.

Well as the weeks go on I will be postings much more of what interests me withing each topic. I do find security to be an amazing area that I will take interest in.

Till next time BYE :)

Horray A New Blogging Spree

2008-05-03T16:27:00.000-07:00

I'm known not to do things unless im 100% into it, well this Condensed Semester is going to be posted here every weekday. Instead of repeating my notes here I will be journalizing my research and finding within a nice 2-3 coherent paragraphs. This will supply the reader with the required information for each topic.

Note: This is Semester 5 of CTY

Topic Titles Consist of :

WIN700 1st half
INT525 1st half
SEC701 1st half
SEC703 2nd half
DCN704 All Semester

I'm looking forward for sharing my experience through each subject indefinitely.

INT420 SSL Encryption and Certification

2008-04-15T15:50:00.000-07:00

ALlow for hyphens make sure your regular expressions are valuable
Display the Format of what you would want in side your text boxes

When you make the user registration validate all the data being entered, is it a valid e-mail phone number, name, come up with the regular expressions to this.

Common security hold is cgi scripts,

Understand the dangers and what we can use perl to pervent this
its called Taint mode

When you get data from a script(a form) so you have to be careful what they
enter in

Run your perl script sin taint mode all you got to do is add a -T anything supplied by the user can not be used in a os system, it will not be allowed to be used for a system call.

if you need to use the data you need to figure it how to untaint it, is to make it its not supplied by the forum but produced by the script itself, the dangers things you can do with data is system calls, system function you're executing a os command

0Back quotes thats dangerous, opening a file through a pipe thats os interaction anything we are doing opening deleting or renameing files, anything we are going to do you must un taint that data
0
e00xample a form were we colelct an 00000000e-mail address, and we want to use the email to email it to the user it will not work in taint mode, cause it can be possible that they wrote in a command like deleting files or w.e they can do to the systemEncryption on the exam,

When we want to send and encrypt data securly, the basic process
take the original data and an encryption key, random string of
characters, random very large number

take the data and teh encryption key and put them into a encryption alogrithem or prgram
what you get out of that in encrypted data, in order to read that data

you take the encrpyted data and a decryption key put it through the same algorithem/program,
then you end up with the original data,

Two basic models

semitrical encryption - a shared secret

with semitrical encryption you have a single key, and you use the same key to encrypt and decrypt the data

asymetrical encryption - public/private key pairs

two keys, that are designed to work togeter, a public and a private key, in this encryption you encrypt with one or decrypt with the other, u must use the other part of the pair, en pri / de pub

Client Machine Alice
AB-----
Connected to the Net
----AB
Client Machin Bob

using this semitrical encryption alas would need a copy of the key and bob will need the copy of the same key

Its good cause its fast,
you can generate a new key for every process/
---_FAST SECURE__----
Problem how do they get the copy of the same key, especially over a line, the problem with session key how do you get the key on both sides

in the past, generate it on place and take it from one to the other and install but again thats a 1 kind operation. Asymtrical alias an encrypted connect4ion for bob, he has the public key B and a private key B the private key never leaves bob,

BOb takes his public key gives it to aliace, she encrypts the data with the public and encryps with the private key,

so the communicatiosn going back to alice are not secure, when we encrypt wioth the private anyone can read it

so its not good coming back in the opposite direction but it does have a purpose,

When he sends it to alice and has the private, what does this prove to us anyone can read what bob is sending, it can only have only come from bob. Because bob only has the private this is called a digital signature, anyone with the public key can read the private key but it must come from that source,

its use for authentication as a signature
Alice can gen4erat her own public/private send it to bob send it and she can use it, heres the problem its slow and alot of work, and somewhat more compicated then it needs to be, in the internet when we want to secure over the wweb we use

SSL ---- secure socet layer, you know this from https

SSL uses all the things that were discussed above, this is how it essentially works

Bob the server alice the client,

in order to facilite encrypted communication, bob needs a public and a private key for bob, now

the admin of bob wneeds a 3rd party company to create a certificate to tell the company this is the company, they take the public keye

they take the public key and send it to CERTIFICATE AUTHORITY, dozens of company's that do this
CERTIFICATE REQUEST, name server e-mail the FQDN all info about the orginations and the computer along with the public key,
the certificate authority preforms sum auth then creats a certificate contains all the info from the certificate request + bob public key then the certificate signs it with their private key, so its digitally signed through the CA.
SSL connection
Alice sends a httpds conn to bob then he says ok then sends the certificate and it contained the public key and the didtal sign of the CA alice reciuves the certificate alices browsers is already wiiht the key of all the private ca's auth, now we accept that public key as coming to bob
BOb has his private key and alice has his public key now alice generates a symettrical key thats only good for this session and encrypts using bob public key, bob is the only way he can use it cause he has a private key

Conenection to his web server his e-mail server it puts the https yellow bar and the pad lock
if you go to Tools page info

You look at the page info and you look at security it tells the identify has been varified by Equifax

View the certificate

In the LAB
Re-install apache to include SSL you need to isntall it into a diff directory you will install OPEN SSL, allows you to generate pub and private keys and request and authority, install apache fresh,
M
M
M
we use to for trust, and the mechinism for a public key then facilitae a session key, then they use that session key

Building a Fast Internet

2008-04-02T07:13:00.000-07:00

http://www.newsweek.com/id/129639

I don't really get the tech side of it...doesn't explain very much but at least their trying to steer away from packet switched networks (too slow).

I haven't been updating TOO MUCH WORK! During my break I will be finishing Uyless Black Emerging Communications Technologies and while taking school in the summer I will be discussing many of the professional classes here on this blog.

Chapter 1 - Introduction - ECT - Uyless Black

2008-03-22T13:41:00.000-07:00

When examining the communications infrastructure and the major problems that are associated with using current technologies we see that the point of new technology is to over come deficiencies of current technologies.

The world is moving at fast pace, processors and applications just keep getting faster and faster, so we look at data communications and how it can improve the movement of information within a networked environment.

This chapter gives the general overview of the emerging technology to meet needs of applications.

Needs for Services
The Past
Development of high-speed inexpensive computers to meet the needs of the average person. This opened a vista to new powerful application. Examples of the applications that may be used are interactive real-time simulations, three dimensional modeling and color images.

The T1/E1 Legacies
1970s & 1980s = 1.5 to 2.048 Mbs
- T1/E1 meet the needs for most user applications

VPN - Share communications channels with other users

Switches - Relay traffic from multiple users.

Frame Relay fast packet service
-Lets the user support error recovery
-bandwidth and demand services
-data applications and some voice applications
-Suppose to solve WAN bottle neck services

MAN IEEE Standard 802.6
-distributed queue dual bus (DQDB) protocol to support integraded networks for multimedia applications
-interconnects LANs accross WANs

Switched Multimegabit Data Service (SMDS)
-Relies on the MAN technologies
-provides public high-speed transport system US and Eurpose
Services - highspeed ata applications that require bursts for high-speed data applications that require bursts of high bandwidth transmission for applications.
Such as, file transfer, CADéCAM, and imaging.

Asynchronous Transfer Mode
- part of B-ISDN solution
- cell relay technology
includes - high speed
- multiplexing and switching services for voice, data and video applications

Cell in ATM and IEEE 802.6 (MAN)
802.6 = basis of SMDS

CELL vs FR

Cell at the CPE a computer or PBX
which can be variable
is - segmented into smaller fixed length units called cells
5 header 48 payload

Supports transmission and reception of voice, video data and other applications

Interests = Large companies that have developed multiple networks to handle transmission schemes.

Why do we prefer cell

Cell is better then variable length frames, which provides the delay to be predictable in fixed length frames with the performance in the network then with variable length frames

-ATM queuing is done inside switch
-Fixed length buffers more easier to manage then variable.
-Cell relay has superior Quality of Service.

Wide spread commercial inception of computer and communication's networks in the 1960`s

1970`s - Communications archietecture was all software
Typically

Physical Layer = hardware
Datalink Layer = software
Late 1970`s early 1980`s
implemented into hardware some of the Data Link functions

Fostered HDLC which would
lead to -Link Access Procedure Balanced (LAPB)
-Link Access Procedure For the D channel (LAPD)
-Chip sets and firmware

Thats all I am going to introduce for now next post will continue Chapter 1, in later chapters Uyless Black goes into detail with every protocol mentioned here and that will be in next post. So don`t be to overwhelmed, I know I was the first time I read half the book.

Little note to me: Ch1 Pg5

About New Postings

2008-03-21T12:01:00.000-07:00

Due to the Hands On Work in my program I will only be posting relevant information on every lecture for my courses.

I will be focusing on, Data Communications,

Book:

Emerging Communication Technology by Uyless Black

that will gradually move to

IP Routing Protocols by Uyless Black.

Any relevant information to courses within the Computer System Technology Diploma will be posted with the Title of the Course Code and Topic, mostly theory.

Note: Future online posting will change.

INT420 - Secure Socket Layer

2008-03-21T12:00:00.000-07:00

Encryption on the exam,

When we want to send and encrypt data securly, the basic process
take the original data and an encryption key, random string of
characters, random very large number

take the data and teh encryption key and put them into a encryption alogrithem or program
what you get out of that in encrypted data, in order to read that data

you take the encrpyted data and a decryption key put it through the same algorithem/program,
then you end up with the original data,

Two basic models

symitrical encryption - a shared secret

with semitrical encryption you have a single key, and you use the same key to encrypt and decrypt the data

asymetrical encryption - public/private key pairs

two keys, that are designed to work togeter, a public and a private key, in this encryption you encrypt with one or decrypt with the other, u must use the other part of the pair, en pri / de pub

Client Machine Alice
AB-----
Connected to the Net
----AB
Client Machin Bob

using this semitrical encryption alas would need a copy of the key and bob will need the copy of the same key

Its good cause its fast,
you can generate a new key for every process/
---_FAST SECURE__----
Problem how do they get the copy of the same key, especially over a line, the problem with session key how do you get the key on both sides

in the past, generate it on place and take it from one to the other and install but again thats a 1 kind operation.

Asymtrical alias an encrypted connect4ion for bob, he has the public key B and a private key B the private key never leaves bob,

BOb takes his public key gives it to aliace, she encrypts the data with the public and encryps with the private key,

so the communicatiosn going back to alice are not secure, when we encrypt wioth the private anyone can read it

so its not good coming back in the opposite direction but it does have a purpose,

When he sends it to alice and has the private, what does this prove to us anyone can read what bob is sending, it can only have only come from bob. Because bob only has the private this is called a digital signature, anyone with the public key can read the private key but it must come from that source,

its use for authentication as a signature
Alice can gen4erat her own public/private send it to bob send it and she can use it, heres the problem its slow and alot of work, and somewhat more compicated then it needs to be, in the internet when we want to secure over the wweb we use
SSL ---- secure socet layer, you know this from https

SSL uses all the things that were discussed above, this is how it essentially works

Bob the server alice the client,

in order to facilite encrypted communication, bob needs a public and a private key for bob, now

the admin of bob wneeds a 3rd party company to create a certificate to tell the company this is the company, they take the public keye

they take the public key and send it to CERTIFICATE AUTHORITY, dozens of company's that do this
CERTIFICATE REQUEST, name server e-mail the FQDN all info about the orginations and the computer along with the public key,
the certificate authority preforms sum auth then creats a certificate contains all the info from the certificate request + bob public key then the certificate signs it with their private key, so its digitally signed through the CA.

SSL connection
Alice sends a httpds conn to bob then he says ok then sends the certificate and it contained the public key and the didtal sign of the CA alice reciuves the certificate alices browsers is already wiiht the key of all the private ca's auth, now we accept that public key as coming to bob
BOb has his private key and alice has his public key now alice generates a symettrical key thats only good for this session and encrypts using bob public key, bob is the only way he can use it cause he has a private key

Conenection to his web server his e-mail server it puts the https yellow bar and the pad lock

if you go to Tools page info

You look at the page info and you look at security it tells the identify has been varified by Equifax

View the certificate

In the LAB
Re-install apache to include SSL you need to isntall it into a diff directory you will install OPEN SSL, allows you to generate pub and private keys and request and authority, install apache fresh,
M
M
M
we use to for trust, and the mechinism for a public key then facilitae a session key, then they use that session key

Back again

2008-01-11T13:26:00.000-08:00

Yep this time I have my light work Load to do more, courses in semester 4 @ seneca,

NDD430
INT420
EAC397
EAC505

Update of the week:

NDD430 first week is basic and should be known and been discussed many times, INT420 is new yet shares common UNIX like programming structure, EAC397 again....I will write my memos, EAC505 fantasy and literature.

A greate site for INT420:

http://docs.rinet.ru/PerfectIntranet/ch12.htm

To the Future

2007-12-23T14:15:00.000-08:00

The bible onto a space less than half the zie of a grain of sugar!

http://www.thestar.com/sciencetech/article/288297

OPS335W11

2007-11-20T19:42:00.001-08:00

OPS335

ubuntu apt-getn install apache
info

sudo apt-get install bind

samaba 3 ways to act as a client

1. you can use a file/web browser that understands the smb protocol

Konquere understands the ftp http and smb protocols

2. command : smbclient
get
put

3. As root do the mount

mount -t cifs //matrix/john.selmys /mnt/banana

cifs driver uses encryption for the password, matrix samba server only accepts passwords in plain text

Assignment 3 (bonus)10%

Write up a document how you will set up a backup/restore system for a client

DNS

1978-79 tcp/ip started

two universities a line between the two, for U1 and U2

then came U3 and came online paying full price

/etc/hosts
each had a host file, information matches forward and reverse mapping, '
registered

1984 - DNS

root servers = 13

Too many request is a DOS denial of service

Vince Surf

Lab 9 Install Bind

DCN386 Frame Relay

2007-11-19T07:00:00.003-08:00

http://www.cisco.com/univercd/cc/td/doc/cisintwk/ito_doc/frame.htm

What does Frame Relay do and how does it work?

Frame Relay - is a modern datacom protocol,
-created to handel a specific job
all protocols specific job
X.25 - Users for small amounts of data infrequently

However
Introduction to LAN 1990
-Require emerged, link Remote area networks together

- LAN 100mil bps

How can you connect this to connect two offices together?

X.25 - top speed in canada 64K----around----not sure-----

Frame Relay, equipment such as routers,
-Have serial ports
-Routers send data using HDLC, ciscos default

HDLC is a module, if you want FameRelay you get cisco to get you the Frame Relay Module

First out of the five.

-Frame Relay perfect protocol for intercommunication for LAN
-its good cause its incredibly fast

Why is frame relay fast?
-It doesnt do anything except transmit data
-Does do error checking, but if their is an error it dumps the frame
-The point is speed

-----------
X.25 do 20 seperate operations, so the packet is preserved and protects
-----------

Frame Relay devices do two things with every frame
-Validate it, error checking, dumps packet if error
-Validate the destination address, dumps it if it dont know it
-It makes sure every frame ZIPS through the network

--We let the end connections worry about the frames.

Where did Frame Relay come from?

A small part of a big initiative put by the ITU
In the future full digital everything
----------
Build the international digital service known as
ISDN
Essentially it failed

ISDN puzzle was examined by 4 companies and saw value in a little piece
Novel Telecome
Cisco
....

They developed the little piece called FrameRelay
-----------------------
Started an organization called FrameRelay Forum,
www.frforum.com
-----------------------
How does it work?

-First confusing thing
-Frame Relay is a DataLink Layer Protocol

----------------------
Phone companies have pre-build Frame Relay networks
ex: every bell office has routers that can handel FR
Idea customers can call bell and attach them into the FR cloud
---------------------
If you have a router of ur own u can take out the HDLC module and put in a FR modeuls
--------------------
Most orginations use the shared FR bell network
--------------------
Bell uses HIgh speed FIbre-optics
--------------------

Frame Relay Format:

f | Control | f

Flags are used when the amount of data is variable
-No specification of data unit

Because their is no knowledge of the variable it puts Flags around the data.

------------------------
Ethernet does 1500bytes
-----------------------

Frame Relay - Combines the address and control field, for the test call it Control

Control Field --- 2 3 or 4 bytes long
^ is known to use

Remember to understand a protocol look at the control field

2 bytes - 16 bits

first 6 bits
- Part of the protocols addressing scheme
second 4 bits
- Also part of frame relay addressing scheme

They are called the DLCI
Data-Link Control Id

| DLCI | DLCI |

In byte one its called the command response bits,
-useless no function

Last bit in byte one is the Extended address
-simply means their another byte incolved
In byte 2 theirs an extended address
- if the EA is a 1 theirs no more addressing

3 bits unaccounted for

BECN -Back Explicit COngestion Notification
FECN -Forward Explicit congestion Notification
DE -Disguard Eligibility

DE - is a key feature

-----------------------------------
Two organization

Have offices Vancouver and Toronto
Happy NEtworking People
-Want to use Bell Canada Frame Relay Network
-Big expensive Routers with FrameRelay Modules
-Bell network Extremely Fast Fibre Optic Cables
TD gets the Routers to the network
Scotia GIrl gets her Router to the network

How will bell build this network
-Bell Canada has a special device at the boundry called a FRAD
FRAD - Frame Relay Assembler Disasembler

Its at the parameters of the cloud not inside the cloud, thats how they attach themselves
to the cloud

SB and TD different data-
How does bell invoice?
-When you phone bell he asks how much data u going to send into the network
-Frame Relay was designed to handel bursts of data
-Designed to connect LANs
20% locally 70% lan
Want to know how big the bursts is going to be,

Range from 64K bps
128k BPS
etc...
Networker, does analysis how much data is going to be tranmitted
and a conclusion to how much data going to be sent and received
Bell bills towards the K
--------------------------------

Frame Relay simply moves the data to the next router, quickly as possible

--------------------------------

FRAD -- Bell canada programs the FRADS

How will bell build this network
-Bell Canada has a special device at the boundry called a FRAD
FRAD - Frame Relay Assembler Disasembler

Its at the parameters of the cloud not inside the cloud, thats how they attach themselves
to the cloud

--------------------------------

DiscardEgibility - gets turned on when you send bursts of data

Bell canda calls bursts of data CIR - COmmunited Information Rate

-------------------------------

Frame Relay has one trick, if it becomes congested, will drop the frame.

-----------------
Getting customers to commit to the FRAD rate if you congest(go over the) CIR rate.
-----------------

BECN -Back Explicit COngestion Notification
FECN -Forward Explicit congestion Notification

When a device gets congestions it turns on BECN and FECN,
Whole idea - intended by frame relay forum, user device would notice
frames will arrive, it was hoped somebody develop a
program to have their own flow control to control the data coming in
Everyone ignored these bits.
----------------

Subnetting:

11.0.0.0

Require 5000 Subnets

00000000.00000|000.00000000

10.0.0.0 internal address

Classless /26

OPS335W10

2007-11-12T12:03:00.000-08:00

whereis ls

/usr/share/man

manare like ls, echo, cat, mv all of these are in volume 1

all the manupages are compressed in gz, its easier to read a small file rather then
a big file to memory to read it,

ls.1.gz

all system administration commands are going to be .8

rezise2fs - volume 8

copy the ls command to your home directory so you have something to work with,
gzip-d ls.1.gz

ls -l
ls.1

now its in a language groff
groff - is a precurses to html

If you look at the html, from html you have xhtml, xml, all of these are markup languages,
before this if you go to 1960, IBM made up GML, they are nothing new they are just
derivatives, some where you will see roff, which is a form, then

groff(GNU free version)

MKGW 8 NOve 2007 mkgw.8 admin commands

mkgw \- Configure a linux host as a network gateway

groff -Tascii -man mkgw.8 |more <---intrepret what it looks like,

gzip mkgw.8

be root and copy it to volume 8 be sure its zipped /usr/share/man8/

On our floppy, we should have mkgw, mkgw.8.gz

show mkgw groff, listing of all the groff listeing and we should also show the man page
bash program as well

chmod 644 <----man page
-----------------------------------------
---------------------------------------
------------------------------------
----------------------------------
Distributed File Systems

All about file sharing, share files between two Dos Machines

The idea is:

Server Client
/
| | | | | |
home home
| |
| |
frank joker
| |
| |
stuff---------------------junk

Make a directory under junk

Connect stuff to junk
Make a file under junk "ABC" as the Server

Alot of things ot be set up to make this work

you have to know the IP address of both machines

1. IP of each machine
"FQDN"
2. Server needs a file sharing program
and-configured to allow the client to read or write or r/w
the stuff directory.
File sharing deamon or file sharing server
It will allow the client to read the directory

Withing our Server we have a file sharing program to allow the client to use this program

3. The client needs a program or software, to attach and use stuff(dir) from the server

^^^^^^^^^^Basic idea od DFS(Distributed File Systems)

The two systems we look at are

NFS - method of sharing files
SAMBA - method of sharing files

Network File System

-Developed by Sun Microsystems 1984

When did the first pc come out 1988,
versions for Dos and Windows,

-important to note,
b/c it was written so long ago it uses ports in a different way

Web Server
-Running Apache
-Port 80 (waiting for connections)-------1024---IE6 (WINXP)
|_1026___Firefox (FEdora7)
|_1024___Safari (MAC OSX)
In 1984 Sun did not use port numbers
-used sun numbers,
ex: SUN NFS Server Sun Client
\(directories)--8----------------8----\(directories)
-The numbers used have nothing to do with ports ^^

This is where
-Remote Procedure Call (RPC)

--We still use the sun numbers but software converst it to ports

When you jrun the server you have to run another program
that changes the number to ports.

man exports ----its in /etc/exports
- on the server side this file tells what directories are avaliable
to which clients & in what mode, read or write mode
Their is an example in the man page
id frank

----------------------

NFS SErver NFS Client(Fedora 7 Client)

-host abc joker on xyz
/home xyz (r,w) $su -
/etc/exports #mount -t nfs abc:/home /mnt
|_usually an empty dir used for mounting
|
# | |
joker clown
#cd /mnt/joker
#rm *
This wi9ll alow the person to do w.e.

If you put xyz (r,w) root_squash
so the rm will fail

or no_root_squash

Setting NFS
1. install NFS-server
2. edit /etc/exports
3. start nfs server

4. you change /etc/exports

5. Choice
- Stop & stop the NFS server
OR
#exportfs -a
-reread the exports file without restarting

READ bout NFS

Samba is different
- Andrew Tridgell -wrote Samba-1995 Microsoft - SMB (used for fily sharing -OLD)
-idea to work in a microsoft enviroment -CIFS (Common internet file system) *newer*
-use windows as a client
- use the share
- can become a client on linux and become a user share
-he also wanted linux with its own share and have
win1 win2 win3 machines just as though linux was windows box
Basically Samaba - A client and a Server, a client for windows shares and a server for windows shares

using smb protocol to see the files in their
konquer - shows file systems and a webbrowser

seneca subnet 142.204
LEARN NFS and
export, exportfs, NFSDEAMON, know how to config the files

Lab 8 is three parts,

Connectings to a Samba server- file sharing server using
cifs - file samaba system
Part One - Client
Part Two - Own Samaba server

testparm - check if syntax is correct

DCN386W10

2007-11-09T08:29:00.001-08:00

Alot of subnet questions in test 2

10.0.0.0
255.255.192.0

Question 2 Test2?

What is X.25 and how does it work?

X.25 when you see a letter then a number you know you are dealing with a protocol or equipement
ITU V.90

SDLC HDLC was last week, in PPP,

but their are different applications in this world,

Example.

A central computer, build a network for lottery ticket machines

X.25 solves specific application issue, if you have an application that sends data
infrequently you need X.25, lottery ticket, its a

Network Layer protocol, packet-switched network.

DCN386 only two network layer protocols, IP and X.25.

X.25 Network Packet Devices

X.25 designed to be a sutible protocol for people who want to send small amounts of data
infrequently.

All the telephone companies have all pre built x.25 network

Bell installed X.25 switched devices that spand all of canada

Easy to install and immediate benefit

Packet switching is already their and ready to be used. X.25.

Tip Top Tailers

because their all using the service is also shared, the second major benefit

It is extremely cost effecient. Pay for the service how much you use the network.

Based on a number of packets ur company of information

Packet is data send through a network layer protocol, IP and X.25 does this.

X.25 will take data and break it into a piece and will be a fixed lengthed, in Canada
Bell canada offeres serveral flavours, 90% of companies, of a basic frame size of 128bytes
this device will build you a packet and the max size is 128bytes.

Theory take user data, break it into pieces and sending it through the cloud.

How does the customer get the data into the cloud,

How does this work?

Simple their are 2 addresses involved,
1. is a real physical address
X121 - internation addressing scheme
-works and acts exactly like a phone number
-14byte address scheme
ha ha ha ha

Number can be up to 14 digits ex: 123-456-789-111

One of are job for us:
Supply the number of the cash register to dial into

The start of the day:

To set up the X.25, he(Manager) will send a packet from the tip top register called
-CALL REQUEST
-sent into the cloud
-goes to the switch, looks at the area local codes
-switch will select a route(path) through the network

The reciever will send a
-CALL ACCEPT

You now have a path way through a cloud,
-PathWay = Virtual Circuit

At the end of the day the guy turns the machine off, a last packet will be sent
-CALL CLEAR
No Longer a Virtual Circuit it is shut down

Another Day:
-CALL REQUEST
A Different Route is taken
-CALL ACCEPT
A Different Virtual Circuit

-------------
The X.25 machines are computer specialized in packet switching
-Lots of memory
Holding-Tables how to get to the Destination
--------------
First address is used in the CALL REQUEST

Once set up a second Address called:
-Virtual Circuit Address
-12 bits ~4096
---------------
VC-ID is sent = virutal circuit 1 - ALWAYS
-talking to 1 computer
---------------
Head office computers talk to Numerous Devices, thousands of lottery ticket machines-
-Identifying 4096 cicuits per physical line
---------------
X.25 Low Grade Low Speed Telecommunications Copper Wire ARgh!
---------------
When you phone bell and ask for an X.25 circuit, how many virtual curcuits on this physical line?
Pick a number -a number 0-4096

Never install more than
-32 virtual curcits in one physical line
----------------Rule of Thumb----------------------------
Cheap phone line!
------------------------------

Confusing Part:

Second thing that we will be asked when asking for the cuircut,

Do you want a private, switched or a combination of virtual circuit
-------------------
Two types of Virtual Circuits
-PVC (Private Virtual Circuit)
-SVH (Switched Virtual Circuits)

Depends on the packet a month you pay for it
--------------------
Another Cost a number of virtual circuits for a physical line

You want all permanent circuits, Bell will install a permanent route through the cloud
--------------------
Why would we used Switched hmmmm yea sooo
Three offices
Three networks
| | |

Every night the offices download the daily sales,
How many Virutal Circuits will i need on this line, One
All the networks in different locations and times will switch it,
-------------------
What if its modern and u want to install on real time, you would need three virtual circuits
and make them PVC

------------------------------------
-----------------------------------
---------------------------------
X.25 most endeering
Most Reliable protocol ever developed
-Error Handeling
-Flow Control Mechanisms
-----------------------------------
---------------------------------
-------------------------------
-Error Handeling (CRC)
------------------------------
-Max 128 bits
-Closest Circuit does error checking
-EVERY PORT IT'EL DO ERROR CHECKING
------------------------------------
------------------------------------
-FLOW CONTROL
- Any activity that prevents the loss of data
------------------------------------
------------------------------------
X.25 does not drop packets
-flow control mechnisms to stop sending data
--------------------------------------------
Because of speed its not used, ^ the things it does
--------------------------------------------

X.25 perfect for customers Infrequently
X.25 people looking over it!
X.25 1 component of a huge body of work
X.25 RULES PAD EQUIMENT TO ACCESS THE CLOUD
X.25 - small amounts data every so often ==== PERFECT ====

Once in the clout Dozen of protocols you can use

You can attached ur PC to Bells X.25 Network,

Phone connectiong, Packet Sender and Disembler (PAD)100$

--------------------------

X.3 - sepcification for what PADS do
X.75 - International speicification

--------------------------
X.25 is the slang to get into the cloud,
--------------------------

WEEK 13 TEST 2, IN THE LAB we are going to go the quiz, worth 10 %,

2 hours of subnetting

and Access Lists. ACL

GROOVEY LIKE GRAVEY

--------------------------

A packet arrives in a router, and the packet has the address 10.1.240.14, router does not revognize
the address and has the folling mask 255.255.240.0 , company network mask.

Class a 10.1.240.14

00000000.0000|0000.00000000

alL U HAVE TO do to see what subnet it belongs to?
00000001.1111|0000.00000000
subnet 31

OPS435W9

2007-11-06T12:20:00.000-08:00

We are going to be covering stuff that is more difficult that what we have done so far,
regular expression, awk, sed language.

Looking at Assignment #2:

A program what makes exchange rate do, take any currency of any country and your program will exchange it to anyother country
from the exchange rate.

Done in 2 stages,

Stage 1, evalaluation varification of input, Nov 16
Stage 2, 2 weeks later

Being Partnersz we are going to use the RCS system

Between the two partners who accounts to use

In that persons home directory ~/asgm2/***/exchange.bash & RCS

710/ 710 / 770/ 770 / 770 /

#GroupMember:
#GroupMember:

The rates are freezed as of today and put on a table on the site

convert.table will reflect the data in that file

cad
CAD
Cad

2arg cad us

Oc can do anything mathimatics

sed -nl | file

We are going to use regular expressions, subject of our lecture today

What are they used for?
To match patterns in data

You can use similar special chars to search for patters in data, called regular expression.

grep 'patt' f1

FNE * - zero or more
RE * - Zero or more of the previous char

FNE . - is dot
RE . - any single char

FNE ? -any single char
RXE ? - is a ? extended regular expression -egrep -awk - zero or one of the previous char

FNE - [!dfds]
RE - [^Fdsa]

RE - ^a[^fds]d - specifies the begining of the line because the other one does any pattern within the line
$ - its the end of the line, this belongs at the end of ^^ that line

.* - zero or more any character, combine those two<---

RE - a\{3\}b - a repeater refereing to the previous char which is a, how many a's their are, 3 a's followed by a b = aaab.
,5 - min 3 max 5, longest pattern first then the shortest

RXE - a+b - extended regular expression - one or more of the previous char. shortest patt ab.

RE - a+b|c?d - the pipe is a or

grep - can use RE - single pattern
egrep - can use RXE - multiple pattern by using the or which is the |

grep 'a+b|c?d' f1 - none are special chars to grep
egrep 'a+b|c?d' f1 - 1 or more a's followed by a b OR zero or 1 c's followed by a d

echo $1|grep '^[0-9]\{8\}$'

(( *sum *= *$?AA *+ *$?BB *))

sed

:S,$ s/exchange/convert/g - in vi

g = globably
no g only first match each line

sed - stream line editor, tell sed what to make to data

sed -op 'address sub-comm/searchpattern/replacepatt/tag' data

some options:

-n
-f
-e

address :

2,10 - only lines through 2 to 10 do the stuff
can also use RE
2,/dog.s/ - start at line 2 next line must have dogs or dogs
/dog.s/,15
1,$ - line 1 to the end of the file
subcommands cover:
s - search
i
a
c

Search pattern:
-RE - here

replacement pattern:
does not use RE

tags:
g - global
d - delete
p

How sed actually really works

has a pattern space buffer,
opens the file takes line number 1 first thing it does check the line number, automatically line 1 goes to STNOUT
Next line comes in #2, address match yes then continue with the rest, if we say s subtitute search for a pattern it will
replace it with that pattern.

sed '/^$/d' f1 - delete blank lines

DCN386 Introduction To SDLC

2007-11-06T06:21:00.000-08:00

SDLC Intro-Continue
P=Primary Unit
S=Secondary Unit

-SDLC is a primary Systems Network Architechture (SNA) link layer protocol for WAN links

-Used with PPP & multipoint links bounded & unbounded media, half & full duplex transmission, transmission facilities, and circuit switched and packet switched networks.

- Network nodes: primary and secondary

Primary - control the operation of other station called, secondaries.

P & S connected by four basic configs-

Point-to-Point - two nodes 1P & 1S
Multipoint - 1P 2xS
Loop - topology P = First & Last S (connected to first and last S)
Hub go-ahead - In bound/outbound channel
P-outb-S S-inb-P
In bound daisy-chained back to the P through each S
--------------------------------------------------------------------------------
Derivative Protocols
- IEE 802.2 LLC is a modification of HDLC for LAN enviroments

-HDLC is a compatible super set of SDLC

-Qualified logical link control is a link layer protocol defined by IBM that allows SNA to be transported across X.25 networks.

-----------------------------------------------------------------------------------
High-Level Data Link Control (HDLC)
-HDLC supports sync, full-duplex operation

-HDLC 32-bit checksum, does not support the loop or hub go-ahead configs

SDLC 1 transfer mode
HDLC Supports THREE:

Normal Response Mode (NRM) - Used by SDLC. S cannot communicate with a P until P gives permission

Asynchronous Response Mode (ARM) - S to intiate comm w/ a P unitil P have given permission

Asynchronous balanced Mode (ABM) - Combined mode ABM - act as a P or S depending on the situation - Occurs through multiple combined nodes - No permission required-

----------------------------------------------------------------------------------
Link Access Procedure Balance
- in X.25 protocol stack
- shares same frame types, and field functions as SDLC & HDLC
- Restricted to ABM
- Can be established through DTE & DCE
- Intiate call P responding S
- LAPB use of the P/F bit is different from that of other protocols
-------------------------------------------------------------------------------------
IEEE 802.2
Three types of service
T1- procides unack connectionless service
-TCP/IP componsate for this
-commonly used

T2 -connection oriented
-ack data upon receipt
-used in IBM communication

T3 -ACK service
-Factory automated enviroments
-where eroor detection is important

Upper-layer proccess use IEEE 802.2 services through service access points.

------------------------------------------------------------------------------
802.2 header DSAP - Destination service acc point
- identifies the receiving upper-layer proccesses
------------------------------------------------------------------------------

OPS335W9

2007-11-05T17:08:00.000-08:00

OPS335

Lab #7 setting up web server using apache,
Assignment 2 posted

Intresting networking type commands:

netstat -an |grep :80|wc -l - how many connections you have to your apache web server

/sbin/ifconfig - to configure an interface, bring it down or up

Commands located in for:
/sbin - administrators
/bin - regular uses

arp - find out MAC address

hostname - tell you host name or change your host name

host yahoo.com - does a dns query which are handeled on port 53, you can also to ip to hostname

ssh username@hotname - its encrypted

scp - remote:/home/me/junk/* . [from] [to]

rsync - sync two directories, if you have host a and host b with 2 harddrive the firstname you do rsync the two harddrives
because identical to the other harddrive.The second time you do it it copies the files that were updates.

tcpdump - print all traffic in the network - nice to monitor what is going on.

nmap [website] - used for port scan - 65000 on Unix -

wget [website] - retrive website information -r whole website tree

Apache Shell commands

httpd - its a deamon

service httpd restart

The very first webserver was called MOSAIC by NSC government computer before IE before Mozilla.

Apache, pached mosaic, Microsoft Webserver is called IIS

50% =====apache
40% =====IIS

/etc/resolv.conf ----short form of resolver---take a domain name and convert it to an ip number

/etc/hosts - names and ip numbers for the local

/etc/nsswitch.conf - order where to look first

/var/log - contains all logging information, want to know what happen to the system \

rootkit hunter- malacious attack suspected

Assignment

A Man page, and a bash script

mkgw

interneral, masquerading

serveral designes

mkgw.8
volume 8 - fdisk

volume 1 - cat, ls

man man ^^

DCN386 SDLC RIPv1 compile

2007-11-03T10:00:00.000-07:00

SDLC - HDLC - FrameRelay - PPP

SDLC - Synchronous Data Link Control

SDLC - Datalink Protocol which are Point to Point protocols

The Bank and customer start a PPP so their is no Network Layer Involved

Website for SDLC frame and ALL information:

http://www.cisco.com/univercd/cc/td/doc/cisintwk/ito_doc/sdlcetc.htm

Below will Summerize what was talked about in class:

SDLC + HDLC + PPP have one thing in common

Variable Datasize
- the protocol does not specify the maximum data unit

SDLC Fields

Flag |- 8 bits of information - 01111110 -|

The first zero start bit last zero end bit.

Why? - To know when the message is over because its variable datasize

Start and End bits - Marks between data.

To ward off mixed data when the bits have a consecutive 6 1bits SDLC will put an artificial 0 at the end aka bitstuffing.
---------------------------------------------------
Control Field |- 8 bits of informaiton -|

A three bit frame format field: Info Frame, Supervisory Frame, Unnumbered Frame

Info Frame
0 - in the control field, means information is being transmitted
Supervisory Frame
1 - Supervisory frame
- positive ack
- Negative ack
- Flow control Feature
Unnumbered - Used For Network Management Functions
- Shut down & restart "Banke Machines...."
--------------------------------------------------------------------
Still in the control field
|Sequence Number| - 3 bits - Can send 7 frames before an ack is demanaded
000 - Received SN
000 - Send SN
Error checking is done for the seven frames

If they are all correct their will be a supervisory frame of 111 for completeness

----------------------------------------------------------------------
Supervisory Frame
|Function Code| - 00 = means no errors
01 = errors
11 = stop sending data
----------------------------------------------------------------------
Unnumbered Frame - 5 bits -
| function code |
- Bring up down reset
- Done by a Network Manager Person
- Preforms network management functions
----------------------------------------------------------------------
Info | Supervisory | Unnumbered
| Poll Final |
- 1 bit 2 functions
- Depends on direction
We call computers usings these protocols
Central Units & Primary Units

Primary unit - control the ordered delivery of data

Polling will ask each primary unit if it has data

- When it is coming from the final primary unit a final bit is indicated
------------------------------------------------------------------------

Thats it for SDLC at this time.

-------------------------------------------------------------------------

RIPv1 - Request Ip address | Hop Count | Interface ...depending on the Hop count it will choose the lowest one as its main route to destination
- Every 20 seconds a request is made
- Does not address Subnets
-------------------------------------------------------------------------

DCN386W9 - SDL HDLC FRAMERELAY RIPv1

2007-11-02T08:33:00.000-07:00

Question 1 Test 2

Test 2 in week 13

Scummed the test AAAAAAAAAHHHHHHHHHHHHHHHRRRRRRRRHHHHHHHHHH!

In the course outline
2test each worth 25%,
1Q 10%
FE 40%

Test 1 20%

60/3

Question 1

It’s a protocol

SDLC- Synchronous Data link Control Protocol

For the 100$ coming out of your bank accounts, you use SDLC

IBM’s protocol very expensive

OSI changed SDCL to –HDLC-

HDLC is ciscos default datalink protocol, if you understand SDLC you will understand HDLC

This is a data link layer protocol
IETF renamed it to PPP, is a derivative of HDLC which is the DERATIVE of SDLC

SDLC insights to half a dozen other modern protocols, SDLC and HDLC and PPP and FrameRelay are lay DATALINK layer protocols,

How do you catergorize it, datalink protocols are PPP protocols

What does this mean exactly,

You and to the bank is PPP no Network Layer Involved, by week 14 why is is not a good idea to put a bank machine on the Internet.

You don’t have to worry about Ordered Delivery theirs only one route

It is stressed it is a Data link protocol,

When you want to learn about protocol you look at the control information that is infront TCP/IP 20 bytes of information in front of every protocol.

He will send us a website with the information to the diagram from this lecture

SDLC + HDLC + PPP and all the things have a
Variable data size – the protocol does not specify the maximum data unit

Ethernet is also a data link protocol it has a maximum variable data size.

If you worked at Scotia bank you would pick the maximum data size, it has versatility you can do what you want with the variable size.

U would say if setting up a bank application down at the bottom of the script would be
MAXDATA : 100

The address 8 bits, 2 bytes long

Lets go through this you ask for 100 bucks from a bank machine it will put the information into the data field, the bank machines surrounds your data with this extra information, a 1 byte
FLAG – 8 bit of information - 01111110
Frame Relay same information it starts with a flag

Why do we need flags, know when we know the message is over.

The reason you need a flag cause SDLC does not have a fixed data size,

Ex: what happends a receiving machines gets a start flag it reads data, onlt when it sees an end flag it knows it has received a complete message.

Start flag and end flag are like book marks between the data.

SDLC will guard against theirs another 6 bits that our not ours, when they all want to send a message the protocols will examines the data, looking for an occurrence of six consecutive ones

While building a frame the data is examined if the software (HDLC) if it ever finds 5 consecutive 1 bits it will stick an artificial zero at the end it will say AH I have a astart frame the computer will then remove the artificial bit and restore the bit, this is called BIT stuffing after 5 consecutive 1’s.

The 1’s are used cause we don’t know the size of the data field

The address is manually applied, one thing to consider, a 1 byte control field,

TCP/IP had 20 bytes of control information, very very inefficient, SDLC 8 bits of control information these 8 bits DETERMINE how SDLC operates, To control 8 bits wonderfully efficiently.

All the protocols we we are going to look at have
THREE FRAME formats its determined by the CONTROL FIELD

This is the first format, theirs a 0 in the control field that means an

information frame is being transmitted, however if if its 1 then a 0 then we are dealing with a

supervisory frame – positive ack, neg ack, and flow control feature

We are doing this with 8 bits instead of 20 bytes like TCP

So we got sending data, error handeling done by the supervisory frame,

A THIRD FRAME

Unnumbered – Used for Network Management Functions

its specially special, Network Management software, theirs number frames with 1 command u can take down and put up

SDLC uses what is called a SLIDING WINDOW (this is the window size), they call this a

Sequence Number
000 – Received Sequence Number
000- Send Sequence Numbers

SDLC can send 7 frames before an acknowledgement is demanded
Totally Reliable, it’s a VERY VERY.

Why 7 frames?

001
010
011
It will senevn frames cause the SN only has 7 frames cause it only has 3 bits,
The seven frames will go out into the internet and the deatination computer will get the 7 frames and then it will do
Error Checking
Under 7 frames CRC on each and every frames
If they are all correct the receiving computer will build a supervisory frame in the reciving computer it will put receive data
111

Function Code
00 means no errors
Supervisors address control and flags

The sending machine sends the other information, once it gets to 7 gets back to zero then starts again

What if their was an error in frame 6, it does CRC error checking.

The receiving computer sends a supervisory frame of a function code of 01 indicating their has been an error, 110.

Supervisory from 11 means stop sending data

Supervisory three things, pos ack, neg ack , and flow control

Whether its an information , supervisory and unnumbered frame, why is it unnumbered, cause they have received sequence number
Information have reveinumber send number

Unnumbered have 5 bits of function code, bring a network down up , reset the machine, 5 bits has 32 different functions, Network Manage Person can do function

Understand unnumbered frams perform network management functions.

Supervisory frames never send data, address control and end flag,

You can send data unnumbered frames, buy your RRSP the NMPerson, here’s a little

The final bit

Pull Final – 1 bit has 2 jobs, depends on which direction the message is moving, with SDLC central computer are called primary units and others primary units, primary units are computers that control the ordered delivery of data

Their can be no collisions in SDLC, think about it,

There is two people and they are side by side and they both ask for $100 and press enter at exactly the same time what will happen

POLLING is used for flow control, hence the name POLL, the bank machine handling SDLC each circuit SDLC will send a POLLING message is a supervisory frame with no data the bit in the middle will be turned on,

It will send it to the new frame ask if it has data pull back and see if it needs pulls the data then it goes to the next machine,

POLLING to each machine, pul indicator primary to secondary

Different if its coming from the secondary unit to the primary unit its called a final indicator bit.

Final frame it know it has received 1 2 3 and there is no more frames, 1 bit with 2 jobs.

Next 5 weeks:

WAN protocol, and Internet protocol, Test 2 WAN protocol questions and Internet specific questions

When you typed router rip
Router RIP- To build something called a Routing Information Table

Two flavours of routing information protocols RIP is the oldest.
RIP V2

Configuring router 1, R1 knows two things, R1 knows about subnet 1 and subnet 2,
R2 knows about S2 S3, R3 S3 S4.

RIP starts up in your router, does something intresting, will send out ever interface it knows and every serial it knows

RIP REQUEST – frame of data – 2 pieces of information, it knows about S1 and S2 and will send it to its neighbour, when R2 gets the rip request will send a rip request, it will say it knows about Subnet3 and Router 3
R1
IP address | Hop Count | Interface
S3 1 S0
*Add*
S4 2 S0

Now R1 knows that R1 is associated with R2 subnet 3

R2
IP address | Hop Count | Interface
S1 1 S1
S4 1 S0

Every 20 seconds when started, biggest problem, every 20 seconds on average it sends a RIP request to its Neighbours.

Another 20 seconds pass so R2 will send everything it knows ^^Addings to RIP: router 1 will *Add*

Second Major problem

IETF webpage, - Specification for maximum Hop count of 15

If you connect 2 routers together it will see that it will be 1hop count, rip will always send it out the fasts, the minimum HOP count.

Next week A FAR BETTAH routing PROTOCOL HA HA HA AHHHHH!

OPEN SORTING PATH is by far a superior protocol, far more complex protocol.

When you type in router RIP its rip version rip, the third crucial failure it cannot understand subnets. RIPv2 does address subnets

OPS435W9

2007-10-30T12:09:00.000-07:00

No double quotes the shell will automatically go into file name expansion, this was one problem with the assignment.
An example with this
Echo $bs|grep [^0-9]

New stuff

RCS

Revision Control System

What is RCS?
What is it used for?

What is the revision number of the current Linux kernel 2.6.28….the second number if its odd its development if its 6 it’s a working version.

What does the 28 mean, it tells you the 2.6 version has been 28 times since its release.
Bugs or any functionality that needs to be upgraded.

^^this is what its all about,

These numbers are not being tracked its being done by the RCS system, lets look at how it works,

We are going to be using this for our next assignment 2, this system will keep track of the changes you make all long, this will keep track with revision numbers like the kernel numbers in Linux, this is used when you graduate when you get a job you will work in groups and your working on a utility of some sort this system has to keep track of all the ongoings, and has to allow each member of the group to develop and making changes, and also prevent people outside of the group to not come in and make changes.

Version Management
You can use this program to keep track of data files or anything, all versions are stored as a single file, for instance when you have revisions there is only ONE file, you can have multiple revision in a single file, with RCS you can keep track of it, or you can ask it to what ever revision you want to work with, the system will go back and undo the changes you have done to work with.

Some commands

-rcs
-ci
-co

To initialize rcs you use rcs –i filename
RCS needs a unique director so we have created a directory called RCS
When you initiate files, the rcs will ask you to give a description what the files about the comma v is added to any file that is created in any RCS system this is created to say it’s a RCS file not a regular file, the file we have initiated it does contain the file of the original file, it has created a RCS shell around it

My New Prompt $RCS
-bash: RCS: command not found
My New Prompt $ls RCS/
age,v
My New Prompt $cat RCS/age,v
head ; version number
access; who has access to the file
symbols;
locks; strict;
comment @# @;

desc
@this is my assignment 1 file from OPS435
@

When you do assignment #2 you will have to give ur partner cause we will be only using 2 accounts, once you make this decision the other person will have to have access to the file,

You have to use the check commands to play with the file, you have to check the file in or check the file out, when someone is on it you cant use it.

Ci jj

This checks it into the RCS directory you never go into the jj,v you have to check it out, you can use
Co –l jj

You want to use co –l because then it will be locked, so no one else can use it and only you,

Ci jj

RCS –a command, to give access to the person, you add the name of the user with no space
Rcs –afcrusso age,v

Rlog to see the history of this file

Ex: rlog jj

My New Prompt $RCS
-bash: RCS: command not found
My New Prompt $ls RCS/
age,v
My New Prompt $cat RCS/age,v
head ;
access;
symbols;
locks; strict;
comment @# @;

desc
@this is my assignment 1 file from OPS435
@

You can branch off to different branches, the particular item will tell you which branch the tree is in.

Make more changes
Co –l age.v

There are a number of commands parted of the RCS system

.rlog – history of the command

Not using this semester

.ident – certain keywords
.rcsdiff – different of versions
.rcsmerge – merge files
.rcsclean – get rid of duplicate copies

Another system CBS and has many more functionalities.

And that’s our RCS.

On warning, if you initialize a file with the rcs –I as you know that’s just a shell does not contain the data of the file, if you were to check out the file, because the file does not contain data it will wipe out ur original file if you continue if will put nothing in your original file, do a check in before you do a check out.

When you encounter during the test some of the simple things, one thing that was expected the bonus question
Regular expressions
Find if $1 is an integer
Echo $1 | grep ‘[^0-9]’ || \$1
[ $1 –ge 0 ] 2> /dev/null
Expr $1 / 1

Thedate:

Cal|tail +3|wc –w
Cal|grep –v ‘[a-z]’

DCN 286 - Information on Ethernet...MORE INFO!

2007-10-25T16:29:00.000-07:00

DCN January 26. 2007

Trying to understand how Ethernet work? What is Ethernet?
Go back in history, the island of Hawaii in the Pacific, in the late 60’s the university of Hawaii had a very clever thought, they had some offices on one side of the island and on the other side, they wanted to communicate between these offices, and their was no way for them to do this, they invented a method, which was satellite service, they developed their own little protocol to send messages to each other, they sent the messages to the satellite and it was a source address and a destination address and of course data, if add wanted to send to add four, the messages would be sent to the satellite and rebound it to the computer. Lets say SA = 1 DA=4, Three would receive the message and ignore it and would only go to its destination. Primitive and it worked. This was called Aloha net. They thought to themselves to send a single down through copper wire. There was a group in the 60’s that developed things like mice, but the most important was Ethernet, and the most was Zerox. ThreeCOM manufacturing Ethernet cards, at the same time IBM was inventing token ring, yet today token ring is gone, Ethernet survived and Ethernet is thriving, December of last year Ethernet people put the standards at running Ethernet at 10 billion bits per second, Then the standardized of 100 billion bits per second. Macaffe invented Etherenet, they put in strands of coaxial cable, DataCom cables coaxial and twisted pair cables, Coax has a thick piece of copper surrounded by a insulated matieral (plastic), surround by a weave, amazing thing about coax the copper is thick and can transfer a lot of Hrz, (hrz dead German guy, working in the 18’s with electricity), the number of wave cycles per second is called one Hrz(hertez), a million Hrz means 100 hrz per second, coax cable b.c its nice and thick can theoretical can handle 100, mill hrz. The coax in the tv can handle 600 mil hrtz, Each station takes 600mil hrtz, Back to MacAfee, we invent a little plug that attaches in the coax, in every comp a special hard that will sit in the expansion slot in each computer (THE NIC) the Network Interface Card has logic, try in to visualize the NIC is a separate device, and has simple logic burned into it, and works with your computer, The idea about the cable was SPEED, A NIC using Ethernet would take data, Operating software uses the inturp and inturrpts the cpu and sends the data, INT52 is a well known interrupt and goes through a specific area in ram grabs the data and moves it to a NIC, The Ethernet guys MacAfee used the follow rules: First the Maximum Transition Unit (MTU), 100 protocols Each has a MTU, All protocols take data, and break it in to pieces the maximum transition unit size is going to be 1500bytes, if you wanted to send 1501 bytes, it would resolve in two transmissions, that is just Ethernet, remember this and remember it NEXT SEMISTER. As the same time in the Ethernet guys IBM was inventing token ring, TOKEN RING when they designed it could send 64,000bytes (huge packets of information), we are going to figure out why the groups made these bye decision Ethernet primitive simple protocol survived, and Token ring survived. When ever a int was sent the NIC would build a frame of data, and infront of it there is a Header, Ethernet header very simple while the TCPIP complicated, HDR has DA SA TL Destination Address, Source Address, A one byte fule called either TYPE or LENGTH. Ethernet uses MAC address, All LAN addresses is how many bytes 4 bytes ip and MAC address is 6 bytes, trillion of address, IMPORTANT’ the MAC address is made up of TWO components, NO two MAC address can be the same, Network standards, the IEEE group Institute of Electronic Engineering (A GROUP), OKAY you are company 999, the first three bytes of the 6 byte address is Manufacture ID, They are identical to AHOLA net, Workstation one wants to send data to Workstation three, the NIC would build the bytes and send it to machine two and ignore the address, and send it to three. Ethernet survived and why…Ethernet was simple that’s the answer it was so basically simple that it thrived, probably for the rest of your lives, you will be working with Ethernet. Test 1 DCN386 questions TWO How does Ethernet work…here is three basic principals on how Ethernet is a base band technology meaning only ONE signal can move down the line at one time (broadband sending 100`s television channels) works CS MA CD, Carrier Sense, first logic in the NIC uses carrier sense, it uses INT52, the NIC looks for digital pulses, if it sees pulses it wont send the data, if theirs no pulses and no one is sending zero data (volts) Carrier sense, no carrier zero volts, no one is sending things, it first makes sure nobody else is using the network, the second pillar of Ethernet wisdom is called multiple access, You can easily simply find the computer on the system , the third is the most important, (CSMA CD), it’s a simplistic design, Ethernet strategy the first work station, the first NIC that detects ugly pulses has a job to do it sends out a high frequency jamming signal, the NIC would try to send it again, Ethernets simplistic approach from this collision will wait on a RANDOM number, > DATA >T L > SA > DA, Zerox ThreeCOM started Ethernet, the original ThreeCOM internet message was like DATA . TYPE . SA. DA, what do you think type stands for…it’s a two bite field that represented which higher protocol, Ethernet has never worked alone it is a delivery boy, a delivery of data. Type (a number) sends the frame to another destination reads the data and looks at the type and understands to send the data to TCP data, it can be all sorts of different TYPE, logic when sending data take note of where its from look at the data and note it should be shot of to TCP program. (HUMAN RESOURCES) IEEE our friends did few things, started making standards which allowed different types of local area networks to communicate with each other. The IEEE came up with the standard 802, this started in 1980 in Feb, they said its going to be called 802.3 and token ring 802.5, 802.11 is wireless, one of the changes was the change of TYPE and made it length, why do you need a length field, well what if you were only sending 25 bytes of data that may or might be not be a important, how does the IEEE know what type of data..they borrowed the first two bites the IEEE solved the confusion of the none 802.3. Ex: Three companies Zerox, Digital Dix, the IEEE solved the problem, today they all worktogether,, not important for dcn 286 theirs a extra thing they put on the frame theirs a preamble, its 64 bits long, 101010101010101010101010 alternating ones and zeros. Think about this you’re a NIC that cost 25$ you can send info to each other, what would happen if you were in a bad mood, and u started sending smaller bits, how does this precision they get insync, very simple very basic that works. Primitive 10baseT 10 million bits persecond using base technology over twisted pair cables, think go Cat5 Cable, Lab wed Cat5 and make the cable straight threw and crossover. Beaware of this Cat5 comes int two types UTP and STP, unshielded twisted pair, and shielded twisted pair. Cat 5 6 7 learn to love next wed. READ up to chapter three.

DCN 286 - Information on TCP....B/C You will be writing Essays On This ALL THE TIME!

2007-10-25T16:27:00.000-07:00

What is ip and what does it do, what is ip’s job, Ip’s job is simple is to get our data through the internet as quickly as possible and that all its job is its job is not to make sure your sure data is safe Ip does not care about that and if it looses you’re data oh well, and not their for reliability all it cares about is trying its little best to send your data through the net as quickly as possible, ip runs not only in your computer, but in all the routers in the internet, client and server, all have ip, gets stuff done fast, you’re going to tell in week 14 about the total length (16 bits) it can theoretically take you’re data and put it into pieces 65,535 K the routers hate big packets, so if you accidently sent a big packet it would break it into fragements, if you approach a cisco router CISCOs default is 1500 bytes, you can change the router MTU bigger or smaller (maximum transmission unit) it uses the identification field so all the fragments have unique numbers, the router then takes a fragment offset value and see which position its on, middle first or last fragments so when all the fragments get to destination computer IP will reassemble the fragments in the original , TIME to live is how many hops a packet can go through the network, you can overwrite it depends on you’re OS, if the router can’t go to the destination it will get destroyed , last thing were going to tell him is the IP address, IP addressing 32 bits of total confusion, todays not ip but TCP, Tranfer Control Protocol, essays on TCP for the rest of you’re Seneca carrier, at first glance it looks very simple but very deceptive very complex, TCP provides reliability TCP/IP running on your computer, in the Internet cloud theirs huundred of thousands of routers, and all the routers are interconnected, the routers are also running IP when you pass the IP packet to the router and examines the destionation address. TCP is running in any server you connect to, what are you doing at home maybe you wanna download a picture of Pluto, www.nasa.org, scattered around the would there are DNS they have two database with NAMES AND ADDRESS, when you contact the DNS server send it a name and will return an IP address, TCP is going to provide realiability while you download the picture to do this it is going to use something called a port, a port when talking about TCP is a number a 16 bit number so 65, 535K, IEEE standards organization which came up with a list with internet application, DNS internet application, TELNET, FTP HTTP, anyone who, HTTP port 80, FTP port 21/22, TELNET 23 we are going to use FTP to download the picture of Pluto, the port numbers 0-1000, are reserved port numbers for legitimate internet application called Well known ports, over 1000 free to be used by any computer, Here you go you got the ip from dns and you know nasa, org TCP doesn’t know the address but attached to IP and its going to build a header information, default header size is 20 bytes and its going to start ot build port numbers destination port Destination port is 21, you can send lots of things to nasa.org you can try to telnet to nasa.org but you want to download something so you are using FTP, TCP will generate a random number will be between 1000, 65000, essentially its going to say this to the client machine to the server what your doing is TCP is opening a session between your client and nasa.org, there is now a session being established, to work correctly, when the seassion has been established the two machines can send data with eachother first open a session then send data then end the session, the session to be established though is a little bit complicated, a client machines sends segment to the server and will flip the two numbers around and send them back to you, here is the complicated part, TCP receives confirmation sends a third header switching it again, the two machines, when they are forming a session are negotiating with each other, before they need to send data, two or three things they must know, most important thing is how long does it takes TCP segment to go from here to the network and back again, the client initiates the second sending TCP record number 1 this machines looks at the system clock on the computer and record the time for the request of the session the little fragment goes flying through the network and sends it back and looks at the system clock again and now they know how long the round trip is going to know how long its going to take, lets just say it takes 1 second, but this machine does not know what it is and is the purpose of the third segment, is looks at the system clock, three headers, now both machines understands how long it takes to you’re computer and the server now it know it takes from it to you, other important things are being negotiated when tcp first came out, back when their was 50 computers and the internet tcp used sequence number and acknowledgement number for error checking, if there is no errors its going to send an acknowledgement number for error handling the sequence number in early days, use to start at sequence number 1 then 2,3(Frames) does not happened any , more, early days no hacking, sequence number was a hackers prayer, todays version of tcp, between the negotiation will pick another random number, you got 32 bits, what’s the maximum number 4 bil and change, so ip when its sending the initial request will pick a random number 0 -4bil and will stick it in the sequence number field (init sequence number) it will start counting at five when it gets it and when gets to the server another random number is chosen, to set this session we look at the little 1 bit of information when the client sends the first header its going to turn on the SYN (flag 1) when it sends the reply its going to turn on the ack bit (1) when it sends the third reply its going to turn of the syn(0) and send a reply, you notice tcp full duplex protocol, theirs multiple downloads, so lets see how it transits data, how weird is it? Where going to ftp to send data FTP, is a simple protocol, once the session is established it starts reading in data one byte at a time, when ftp thinks its got enough for one segment it will screen the data 1 byte of a time, and codes the bytes 1, 2, 3(bytes) if you left tcp alone it will leave it in your computer it would literally blow your memory of your computer, TCP says I think its enough data (100) bytes and knows the intial sequence number was 5 now its 105 and its going to do error checking on that 100 bytes, using Checksum an algorithm that makes sure theirs no bit errors and if there is no error bit its going to build the acknowledgement number 106, and turn on the acknowledgement number, then the server goes onto the next 100 bits and acknowledge number is going to go to 205, the data gets send tcp does error checking, the machine will build a twenty byte header and positive acknowledge number 300, if you peer closely of the little 1 bits their was a error, what would the server do? What tcp does is unique, TCP does nothing, TCP was written in such a way, TCP looks at the system clock and record the time, if theirs not a positive ack in 1 sec, tcp will automatically retransmit the packet, TCP will notice that the two packets with the same sequence number and discarded one of them, at the end of the session and all the data is sent it goes through a complex procedure to close down the session and we don’t have to worry about till next semester, Window the third thing the initial size, depending on the OS, link between tcp and the operating software, if your using Windows, windows will direct tcp will have an initial window size of 64K, Linux has much smaller window sizes 2k, the bigger the window size the easier you make the hackers job, when the session is nogiated it’s a initial window size, two tcp start sending data, lets say they start small window size of 2k, tcp will actually monitor the number of errors are their, if tcp ‘thinks’ the network is good today because of no errors either machines can increase the window size, and if even more it will increase, tcp increase and decrease the windows until errors start happening, window size is really how much memory is going to be reserved on each computer, the application determines how much or when to send data, it tells tcp heres enough data, and will turn on the push flag and could receive the blocks of bytes and save it in number, when a tcp receives a packet when its turn on it will saveit and push it into the application, its how much memory in each machine is going to be used, ultimately IP is going to see the packet size, Window size is the amount of memory to save multiple tcp pieces, Urgent Pointer and Urgent bit till next semester, for now all we have to know is TCP header and a big pile of data following the header, lets say for some reason the application wanted you to read a specific data that not right on the front it will turn on the urgent data and will read the password which was 100 bytes in, save till next semester. TCP and IP are mentioned numerous chapters into your computer, write essays in week 14 and put these two topics in test TWO to get some practice.

TCP
Source Port(1001) | Destionation Port (21)
Squence Number (00000101)
Acknowledgement Number
Data Offset| Reserved |URG(1)|ACK(0)|PSH|RST|SYN|FIN | window
Checksum | Urgent Pointer(1)
Options + Padding

VERSION IHL TYPE OF SERVICE TOTAL LENGTH

What is a collusion domain, HUB with ports, you got a HUB the simultaneously the collusion will interfere with all the toerh computer, and the chaos is extened to every machines (CD) and the more machines the more chance of collusions happening, Switches are employeed to reduce the effect of collusions of your network, switches break it up to separate collision domains, SWITCH 5 ports and traditional little network hubs to each port and then attached to networks, no the hubs machines are in a collusion domain but if a collusion hapends here and will have no effect on the other domain, Switches reduce the collisions, everything we put on here is its own little collision domain, today happy networking use a process called micro segmentation, what does that mean, networking guys today have virtually eliminated collision through high quality switches and having one machine on each port on a switch their can be no collisions , micro segmentation imply switches and are all into switches Cut THREW switch does what, when a cut threw switch reads the frame it immediately checks the destination address, will immediately set up a channel source and destination port, if you got a nice safe environment, Seneca college, you use cut threw switches, how ever if the environment is a little shakey, in that environment you use STORE and FORWARD switch that has huge amounts of memory and will read the face and its entirety and store the frame where it does error checking, and if the frame takes it and there is no errors it will send it to its destination,

Does not matter which but it can get to one work station through its port, now we want to talk about subnets, switches are datalink layer devices routers are network layer devices, we are one originations and we sell stuff on the net the switch to the computer and the server, we need to sell stuff on the net so we need to buy a router, we need a domain name, our domain name has a associated ip address 200.1.1.0 (ClassC) we hire a networking switch 200.1.1.254, we got a problem cause were in Toronto and going to Vancouver, to they subnet to create it so they can expand and have their own portion, to create subnets its an easy thing don’t matter what class, you create them the same way you play around with binary numbers,windows create subnets a dumb way, and use a short cut and don’t know when there is a lot of subnets, the correct way is to play with binary numbers, which numbers
Network Address 200.1.1.[0] in control of the 4th octet, to create subnets take the host bits and write them out in binary one rule to be applied to subnets by convention we never use all zeros or ones, so we have two left to indicated subnets 00 01 10 11 so 01 becomes Toronto while 10 becomes Vancouver. [00]000000 to indicate if its Toronto or vancouver
SN
00|000000
01|000001 [65]1*
01|111110 [126]2*7th -2
11|111111

We turn on the host bits and the subnet
255.255.255.192 which is the value of [11]000000
1* the address can be added for example 010000010 and moving the 1 up to the numbers
The last number and the range there for becomes 65 – 126

Vancouver
SN
10|000001[129]
10|111110[190]

NOW WE NEED THREE SUBNET IDS with 001 = T. 010 = V 100=LA
001|00001 [33]
001|11110 [62]

DCN286 - Information on IP...GOOD INFO

2007-10-25T16:26:00.001-07:00

Browsers are not internet applications,
HTTP, TELNET, FTP, DNS --- APS
All internet applications were written so they can link with the transport protocol, all these applications work with TranferControlProtocol and UserDatagramProtocol , you can do a lot of things with this write C++, Two guys wrote YouTube.com they used an idea that anyone in the room can do, they wrote an internet application that was very successful, the science behind it is common, DCN386 writing an internet application program…they use a ApplicationProgramInterface…this tool will hook this application right into TCP or UDP, TCP what does it do? Tcp does very little actually it provides reliability into your internet transmission, here is beautiful drawing of the internet CLOUD with a bunch of router drawings along with you on the side at home on the net…and on the left the ISP….The first thing you have to know about the internet and how ti works when you send packets of data in to the internet you sending it into a hostile environment…it is dangerous inside the cloud…ROUTERS which we think is a our best friend…it turns Routers hate packets they detest them they only get rid of them, but the easiest way is to move it to the next router…because its such a hostile environment TCP running in your computer and the SERVER in which your contacting TCP tries its best when Routers destroy you packet TCP will contact the server and ask it to retransmit the packets…TCP will keep trying and keep trying a router does not know anything about retransmitting stuff…so TCP just runs in servers or clients it doesn’t run in the internet its reliability in each end. UDP on the other hand is a stripped down version or TCP…error handling is not in that UDP is unreliable while TCP is reliable…Why would they use the unreliable and a reliable, UDP faster then TCP, depending on what you want to do…the rule says if you sending tiny packets into the network…use UDP because the chances of an error is small so send your tiny packet through the net as fast as you can…ok lets look at a lot of a big picture…going to nasa.com to get a picture of Pluto….nasa.org will create DomainMain(its Name(lol))Service…global system where you type in nasa.org and it will go find NASA’s ip address…so your typing it in and DNS will treat it as data and will look at the data to the closest DNS server….its a tiny amount of data…What do you think DNS uses…obviously UDP…DNS always uses UDP…okay you got the ip addresss… TCP will pass to a program called IP and will send info to nasa.org that has a big file..pluto.jpeg now that’s big files and its going to be downloaded using FTP its going to download a lot of information…big packets are involved…what do you think FTP is going to do? FTP is running on the server nasa.org…it read the file and sends it into the internet FTP always interact with TCP because it doesn’t want any mistakes these two programs only run on the CLIENT or SERVER machine they have to no part into the Internet…it just knows reliability. How does TCP get itself through the network it will read the |data|F(header file)|TCP puts a lot of control information on it 20 byte header to be exact| this then passes down to IP everything uses IP…this get passed down |data|TCP|IP(20bytes of control information|), both have 20 bytes of information its 40 bytes of information must learn all 40 bytes for test two…TCP can deliver anywhere in the world…IP doesn’t know how to get into the cloud its great when its inside the cloud but it has no clue on how to get in their, what does IP do it sends it down to 802.3, NIC you put in it’s a Ethernet NIC…Nic will send it and you ISP is inside the cloud. Ethernet is going to deliver that packet from your computer to your ISP…whats in the Ethernet |data|TCP|IP|Ethernet … when the ISP gets the packet it gets read of the header and strips it off and passes directly to the Router inside the cloud Ethernet delivers the data. Now the IP packets inside the cloud it can be delivered to the destination Address..when it gets close to the router where the information is …its forwards through the routers and before it goes to the ISP and is re-stripped from the Ethernet frame. The internet is a popular their. IP we have to figure out how IP works….first thing we have to know about IP IP like routers does not care about your data…it doesn’t careless if you packet makes it or if it doesn’t. IP makes the best effort through the network as quicklWy as possible…HOSTILE. Where going o look at 20 bytes of infor
0 4 8 16 19 31
| Version | IHL | Type of service | Total Length |
| Identification | Flags | Fragment offset|
| Time to live | Protocol Header | CheckSum |
| Source Address |
| Destination Address |
| Options + padding |

The very first bits look at Version it will look at 0100 the binary level which equals 4 it will all have four bits of information…sooner or later your ISP is going to be version 0110 version 6, a couple of years ago he would say version six will be introduced right away…the IP address is 32 bytes long…the classes made it less effective and proved to be not a great idea and ran out , for a start the IP header has 128 bits, when IP version six comes out, he can go around the world in one square feet increments, in version six each square foot will have million in the square foot…the reason were not panicking anymore came up with something Class List Ip ADDRESSING because of that the full amount of IP address can now be access and now it is being revised…somebody’s brain wave made v4 not needing v6 but Linux. Their will be a compatibility with each other v4 and v6. The next four bits are equally boring Intial Header Length….(20 octets (20 bytes)) if we were creating are own internet application and wanted to test it out we would use something called options…Options is a little bundle of tools that will let us test are application…never do unless you writing your own internet application…..Ever heard of a little application Python…he took look of Python and thought of us…Python already has (application program tool kit to write applications) Python just installed in the Cisco lab…make your own client and make your server…...Type of service.. IP is probably the same age of us it was written quite a while ago..its been around for a couple of decades for 20 years all routers in the internet ignored the 8 bytes…all of a sudden few years ago its become the hottest 8 bits Quality of Service in Networking, we got to worry about the 8 bits…something happened recently another internet ..downloading Movies Voice and Media…Type of Service came important some packets are going to have priority of other packets. Router has serial ports and Ethernet ports…packets come into the router… routers temporarily store IP packets were talking nano seconds it just buffers them in old days they would look at ToS but now routers are starting to examine this Type of Service, this particular packet is in the middle of the buffer but has quality service and will process it first…just understand that some routers can treat some packets as priority packets…Total Length…that means that Total length for Data|TCP|IP the data and the control information ..Ponder how big can an IP packet can be 65536 (64 k) that is a big packet…64 k packet if you were foolish enough to write a program to send out 64 k you would be sorry…. Routers hate big packets they despise… they wont destroy them they will take your big packet and chop it into little fragments of the original packet… all routers do this… hard to comprehend.. when we go to cisco lab on wed and we look at the router and start configuring the router they have a default maximum tramission unit size… if it receives a big packet it will be MTU’s its 1500 bytes… because that’s what Ethernet uses….Lets drop a nice big packet | 4500(chop into three) |(20 byte header)

| (1500)[ID010] | (1500) [ID100]| (1500) [ID001] | - contained in the header info is the destination it chops up and put the header infront of each fragment.

How does the server know that they all belong together because the server gets all the fragments has to put them back together HOW DOES IT KNOW the three fields of identification flags and fragments offsetthis is what indicates the fragments belong together…IP before it sent the packet it picked a random number and put it in the Identification field you’ll notice it will be 16 bits its going going to be 0 – 65535 bytes… when the router breaks the big thing into pieces each fragment will have the same identification number and knows they are fragments and have to be reassembled back into the frame ,….wait theirs a problem went different ways…How does IP manage to reassemble these three fragments…they would look at the fragment offset...
|5000 |3000 |1500 | |byte 0 its going to read them and store them temporarily in memory…it takes the data read the offset and puts it in memory but by the OFFSET of 3000… it takes the 5000 and puts it the 5000 OFFSET…sequence failed, what if the sequence 1 get into the a grumpy router fragments can get fragmented….The Flags are three bits long…only two of the bits are used the first bit is a strange bit.. if the first bit is turned on that means that ip examining this it means DO NOT FRAGMENT its called a do not fragment bit…it was originally designed to send out and see if you get anything back… if a router got that packet with the do not fragment it will destroy it… the second bit means Last Fragment Indicator, this is used so after it knows it has all the fragments because of this bit. It knows it has the last one in the series…8bits Time to LIVE….what does TCP/IP care about to time to live… what if we purposely put a destination address that does not exist, theoretically our packet can go through the world…Time to live when your IP sent the packet out it put a value in TTL it will be some value from windows to LINUX from 1 -255 and the default value is 32bit, it will subtract the value and it will eventually go to zero with the zero packet will destroy it….sending a packet out of Seneca it probably …www.bagpiprepaire.com do a trace route and you’ll see it…. Protocol not a very important field it simply means TCP create the this packet or did UDP create this packet, and will use a different code for each so when the packet delivers the packet it look at it and will be like deliver it to TCP or IP. code maintained by the IEEE, IP can run with a lot of other protocols…Raw sockets, you just use IP on its own… third code….IP does not care about your data….Header Checksum.. Does IP do error checking…yes it does error checking only on the Twenty bits and only looks at the the IP address….WE have to totally understand the IP address because in test 2 we are going do questions called Subnet ting questions and to do Subnet ting we have to understand the IP address really really well. Early start on subnetting. Guys that created the IP standard, origanilly created class addressing… what can you tell to determine the class of the address you simple look at the first byte. IP addresses are four bytes long.. class a determined looking at the first byte they all have a zero of the first bits of the first bytes leaving seven bits , the other three are Host address and class B are 127 (127 is special called LOOPBACK. Used for testing) B 10111111 128-191 C 11011111 192-223, How many class a’s 126, 65535kb, class C 254 hosts. Working in groups of two ooo, we want first stations to the other station through two routers what have to do to achieve this is do something configuration file, basic configurations.. apply IP address to the PORTS we want to apply ip address to those ports.. they will learn how to send stuff through a network… all we do is provide the initial information and press on the routers will figure out what to do, Lets say have an ip network and were going to use a class a address 10.0.0.0 that number means the entire network but to a router they don’t see one big network but THREE subnets, how do we break it into three subnets we are going to use a Subnet Masks, this allows you to create these subnets in the first place… you see if we just had the network number and we plug them in we wouldn’t know which router can get the total packet.. so we use the mask 255.255.0.0 if for some reason we didn’t wanna create subnets we could give an ip address 10.0.0.1 we have to put a 10.0.0.1, 2, 3, 4, 5, 6 in each port, things get broken into subnets…we wouldn’t do it without the subnet and we would still have to have a mask and have a default mask 255.0.0.0 a one byte means this bits parts of the network ID if we wanted to know subnetting we take the second byte and will be used to indicate the bits are subnet bits hence if we wanted to do that we make 255.255.0.0 11111111.11111111.0.0.0, we will change the purpose of the bits and when the router recivies the packets will receive that packets one being the counter and one the subnet….Look up subnetting…

WIN310W6

2007-10-17T07:02:00.001-07:00

Last we talked about was root, cash.dns is the root file,

Type of name server, name server is a dns server, FQDN.

Hello.uk are primary, primary zone on the primary server, is the athorratative zone, only 1 primary dns, but can add as many secondary dns, different physical machine, used for backup, load balancing, save bandwidth and connection time. You can promote the secondary to the primary.

Master name serer, responsible to send updates to secondary, can be primary or a secondary, zone transfers from primary to secondary, SOA has a time time limit, and the primary is also responsible to update the second, these are replicas of the main DNS server, Now who is the master of 2 and 3 it’s the primary, there is flexibility here, 2 can be the master of 3, 3 does not have to know 1 but knows 2, 3 will query 2 for updates while 2 is getting updates from 1. OH YEAH SO 1 to 2 to 3 is 15 minutes, if this occurs every 15 minutes the 2 waits 15 then 3 waits 30,

Caching does not have a database, everytime it resolves something it caches it and resolves it for a specific time, u use it so after u don’t need to maintain and the other for quick resolution, SOA start of authority,

AD every single machine is a cheef, makes it so you can go to every location and do administration, and add a record, the record will be replicated on the other directory servers, every single DNS has control over the zone, how would they know which is the latest up date there is a counter, as the other dns respond they look at the version number and the remainder will be sent which is the updates of the server,

Resource Record, what type can we put in the DNS, pg 74, the ownerm it identifies the resources record and who it belong to, name domain the host, this I s basically the owner, there is TTL time to live the life to it, class Internet class, type of record what we doing mapping name to ip address, mail server to a server,m several types of records we can input, cantains resource data, something with the record that is associated with 32 binary, which is the ip address.

SOA – start of authority, original point of domain or zone, the information in the SOA it shows the authoritative server, this is the server hosting the particular zone of domain, you can create as many as you want to, this is is the guy that will be responsible for everything’s, serial number….every time you manage or update the dns is increases by one so because it haws increased u have to give the updates to the other zones. This is the negotiating item.
DNS PORT 53 UDP FOR THE QUERY
53 TCP FOR THE UPDATE

Name server, DNS server responsible for the zone,
A record is a recourse record, the purpose for the A record is the mapping of the assosiacted IP address. 32 integer. \

PTR – point of record, record of a reverse look up. We say what is the ip address of venus what is the name of the ip, its called venus the planet.ca, we need when we have applications have th resovle the name through ip…..from ip address we grab the name

CNAME or an Alias – mapping of a conanical name to an established name \
Like when we go to Seneca cs = cs.senecac.on.ca

Another example- an ftp server, and the name was, ftp, ftp1.banana.ca it can change to ftp2.banana.ca but when every one is conneting they are connecting by ftp, what they are saying is to make an alias, and redirect it

MX = Mail Exchange pg 77 bottom, is in fact is the server that is willing to host your mail, you can have

10 ns1.mail.yahoo.com
20 “”””””””””
50 “””””””””””

This is the priority in which to send the mail.

SV – service locator pg 79, allow to specify server to application, an example is Active Directory, that relies on the server record, and Also
NetLogon Service, this service carries info from the desktop to the server. For example your user name password and domain name.

Two types of queries, Iterative and Recursive

What is a query, it comes form a resolver or the client looking for some assistan what does he want, please tell me the ip address of this particular host,

Iterative, gives you a refferall, the client is looking for sales.contoso.com, he goes to the dns serer, and the dns server gives him an answer to go the .com or root servers, the client himself goes to the other servers gets the answers where contoso is goes to contoso for a name of sales which is sitting within the domain, and obviously gets the ip address for sales.contoso.com, the client has done the work, who cached the information the client.

Recursive, the priouviously the client have done everything, now the the client submits the query to the local dns, asking him what the ip address of sales.contoso.com, and the client waits for the DNS to do all the chasing.

WINS and DNS are in the same business, they both so resolutions, name resolutions, dns sports car, WINS truck, DNS FULL qualified domain name, DNS does FQDN, WINS NetBios, NetBios are computer names, computer23 or 24, wins is faster, but it only works on Microsoft networks. How do they work?
‘
In the dns point it to WINS..

Look what happens a client wants to do DNS. WINS handles 15 chars, the nature of it.

DNS creates a WINS, DNS will truncate the domain name and leave the ACCOUNTING name, dns gets is from wins, then dns puts back the family name into the Microsoft.com

Four types of response you get from the query,

Positive this is the ip address, an example can be something from the cache,

Authritative main server primary server or secondary server

Referral – Iterative nd Recursive
Negative – Answer it don’t exist

PG 87

Zone Transfer – Notify –

AXFR – FULL – launch a secondary DNS
IXFR = Incremental –

Fires a queryin the soa and looks for a response, tcp

Iterative load on client
Recursive load on some other machine

Conditional forwarding you can add more stuff in it, 2 companies for faster resolution to the specific company……microsoft.123.123.321.333

DCN386W6

2007-10-17T07:01:00.000-07:00

TCP – get you’re their correctly provide realibility, the network can move your data through the network which is highly error prone, Routers only know IP,

Tcp is only run in client, passes data in ip and pumps it into the internet and goes through the network at high speed, at the other end there is another server.

You can write software that only uses IP, TCP cannot exist on its own, their no purpose for this.

Some are connection-oriented, and some are connectionless, IP is connection less, TCP is connection oriented, that means TCP establishes a session, to establish a session with another computer probably with a server somewhere in the world, to do this, the Cisco course calls it the three way hand shake, This is the tcp header when you log into the internet and try to create a session, your client machine will send 20 bytes of control information,

Source Port, Destination Port, a port is a number a special number,

Few internet applications HTTP, ftp, IEEE got a lot of application so they gave them a number HTTP:80, Telnet:22, FTP:20:21, these numbers are well known ports.

FTP work with TCP to give you a nice picture, TCP will provide the reliability, the

Destination Port will be 20

Source Port – Random number greater then 1000,m less than 65,000, the server knows theirs a session random 6666 SD, because other people want to log in and it will pick another random number for the other client machine.

Something can happen where they pick the same random number, what will happen in this case it will not work cause the session will be already established

This leads us to the three way handshake, when the client request, the server will send 20 bytes of information, SP DP,

Why this three way thing the client and the serer, are establishing certain factors, they are negotiating the parameters that are going to be used in the session.

Clients initiate session, servers never initiate session

the first 1000 numbers are reserved

For test one, only worry about a couple of things that are being negotiated during the three way handshake.

TCP is viewed as a streaming protocol, it streams data from one computer to the next 1 bytes of a time.

Ftp all it does rid stuff of ur data and pumps it into tcp, and tcp starts to carry the bytes 1 2 3 4 5 bytes, its carrying the bytes cause it doesn’t want to loose any, it wants reliability so it counts the bytes.

The Sequence Number ( 4 bytes long )and the Acknowledgement number (4 bytes) keep tracks of the bytes that are transmitted.

Old days the sequence number would be 1000 bytes and so on, so one of the things that is negotiated when you connect to a server, 1st version started at 1, great for the first years, when the internet what new, when you wanted to hack into someones session, you just had to predict someone was establishing a session, you can muscle in the three way handshake and interfere with the process,
What sequence number are we going to start at?
Now it is a random number something between 0 and 4b, one of the three things a three way hand shake does when you send the tcp header it will pick a random number 0 and 4billion.

So SP 6666 | DP 20| SN 2|

Also another bit called the sync bit, the server will flip SP DP, the client machine will pick an initial sequence number, the sequence number is a count of a number of bytes by the tcp program, tcp counts the number of byes, it don’t matter what internet application it is, every byes it precious, the initial sequence number where it will start counting from, lets say its at 100, and tcp receives 100 bytes from ftp, it going to send 100 bytes, because it started at 100 and sent 100 it will then be 200, the server will do error checking, Checksum, it will send back to you in the Acknowledgement, and it will say it got 200 and the next byte it wants is 201, send another 100 then the SN will be 300 and the ack will be 301.

The first thing tcp doing is both machines establish an initial sequence number, they do this by sending one header, the second thing that happens when sending the three way handshake,both macnhines must have a good approximation on how long it takes to send a packet to eachother, tcp relies on time, a great deal, tcp operation relies on understanding how long it takes to send and to get the reply back, don’t forget the internet data can get lost in here, tcp is more accurate than 4 seconds, when the tcp tries to establish a session it will record time on the systems clock, then it will send the packet and send it back,and it will know when it sent and receives stuff, but eh server must also know that’s why we have the third hand shake, the first and second establish the throughput time rate and the third packet is send, then the server machine knows how long it takes from the client to the server and server to the client, vital for tcp, tcp is a weird protocol, TCP all it wants to know how long does it take to send and receive a response.
(IP puts the data in correct order) tcp counts the bytes, makes sure the sequence and ack are consistent,

Two tings negotiated, is identifying the initial sequence number, making sure both machines know the round trip delay time, establish a session number and a time related to sending a receiving data.

Acknowledgement number, - when you send 1000 bytes the client machine will do error checking it will send 20 bytes and it will say ive received 1000 bytes the ack should be 1001, the next time 2001, the next time it will be 3001

ACK 1 bit – a positive acknowledgement, the ack means a positive ack that means your tcp has done error checking on the data you have received. No such thing as a negative ack. Tcp is the only one that does not have an negative ack. If the server does not get a positive ack it will resend the data to the client.

Window – size – is influences by the operating software that tcp it running in, first big surprised TCP works will the OS you are working with, it influences tcp, How big is the windows size, tcp receives data and it counts the bytes, it has a max bytes it automatically sends it. The max amount of bytes is the window size, its 2 bytes long, what the max value, 64k, fact the bigger the window the window size the easier to hack, Microsoft has 64k, Linux it depends like 1k,
2nd things you have to know, its not fixed its a dynamic number, during the actual transmission of data the window size will change, window can start at 1k increments, tcp is changing the window size dynamically, both tcps will send the 20 bytes with or without data increase or decrease the window says, the number or lack of errors,

CHECK SUM – CRC standard error.

Nothing about the urgent pointer, nothing about the last thing,

Fin 1 bit - the server is sending thing to you , the very last byes by the server the final bit will be turned on

First initial sequence number
2 establishment of round trip time
3rd windows size

Ethernet

What does Ethernet do and How does it work?

Its still evlolving, the IEEE and other groups, its still growing protocol, things Power Over Ethernet…..so many….back to beginning.

Created in Xerox corporations, they invents a NIC using a very simple protocol, they called it Ethernet. The reason this survived, far more technical things like Token Ring, why this dispeared it was so simple and basic it literally cant go wrong, its easy to install, a NIC has this,

Tell him next week
Ethernet also known as 802.3 operates on three basic principles, the first principal is called
Carrier Sensing – listen to the wire,

Ethernet is braod band tech, it means it takes the entire bandwidth of the cable which means only one machine can be sending data at a time, here we got four machines on the network, with one server how does it know its not being used by the network, the NIC has a volt metre, send data to nic it compares to data to be tranmitted the volt metre will test the cable to see electrical activity, if theirs zero volts then the network is free, so the nic takes the data sends it, data is not sent until until the network is free, CS,

The second attribute is something calle Multiple Access, fancy way of saying at any point in the network you can install work stations, and it will work admidately, every NIC has a unique MAC address, IEEE will give you a manufactures code number, each NIC has hardwired address the the first three bytes the company, the last three is a sequence number, all nics have different addresses, you can simply attach workstations and they are operational

The third attribute of Ethernet is Collision Detection, it’s a very simple thing, bad form of connection control,

One machine access 1 some 9, both test the line at the same time and both realize the network is idle, they do it at the same time, this results in the two machines building the thernet frame and sending it out, what happens the pulses will destroy eachother, the more machines the more collisions, Ethernet knows it happens Ethernet has a strategy, any machine, the server detects nasty pulses any machine, the NICS are constantly doing this, any machine on the network that discovers a collision sends a very special frequency like a squeal, a jamming signal, to every machine on the network. Both machines retransmit but not at the same time, this is the smart trick, when collisions happen they wait a random amount of time,

The Nic builds the Ethernet frame, the os sends data to the NIC the NIC builds the fram out of your data what does the frame look like, NIC a little bit of memory, what does the frame look like, it will take yuour data and break it up into segments, packets, how big is an Ethernet frame

All protocols segment and reassemble ur data, takes your data and breaks it into frames, the max size of the frame is 1500bytes, breaks data into units called bytes infront of the 1500 bytes its puts header information the
Source Address is the Mac Address 6 bytes long, three bytes man three ,
DA also six bytes, in theirs
2 bytes that can be confusing, is the length of the data.

The IEEE stepped in and all LAN to work together and standardized things and made a change to Ethernet its going to be Type Field.

NOVEL oracle data is a type, apple talk a type, all modern NICs have a type field.

IEEE first couple of bytes indicate length

The front 64 bit preamble 10101010101010101010101010,, used the sync transmission of the frame every frame establishes sync through preamble.

Last piece of into 4 bytes, very effiecent error checking CRC or FCS,

Some equipment such as switches actually do error checking, but there is no provision in Ethernet for handeling erros, NICS and switches do error checking but if there is an error dump the frame, there is nothing in the header for re-transmit the packet.

Ethernet is a delivery boy it relies on high layer protocols to handel any errors, designed for speed.

After reading week CS changes to CA, when u get to gig connection.

Theirs a min for data which is 46 bytes, it will pad the rest of the bytes if its smaller then 46 bytes.

OPS335W6

2007-10-17T07:00:00.001-07:00

Lab 5 is due two weeks from tomorrow, Thursday before midnight, this is the break week its due.

Dealing with directories on unix and linux, we have a problem with size or space, this is is the old way on how to do this

A hard drive sda, you have three partitions, sda1, sda2, sda3, you could have had swap, /boot, /, 500, 300, 5g, we are looking at the sda3 5g it is the root partition is contains a file system, so he has the root directory he has /etc /usr /lib, after we format is its ext3 file system, its taking up the whole 5 gigs, take sup all the space in the container.

Mkfs –t ext3 /dev/sda3
In rescue mode you can format it,

We have a physical partitions and inside th partition we have a filing system, what happens when it gets full, In the old days you would go into fdisk /dev/sda, in fdisk you would d 3, its gone, your just deleting the partition table, not the fs out their, the new 3 now its gone, then you would put 6 gig then you would put write if you were to reboot the system you would still have the fs in their but its not using the full 6 but the 5, after that you reboot, you do the df command you see the root partition is 5g, you can now resize2fs /dev/sda3 , made for ext2/3 fs, when you resize this you are getting more space put into the filing system.

1.fdisk /dev/sda
D3
N3
6gb
W
2.reboot
Df
Resize2fs /dev/sda3

Expand your filing system to use the whole partition.
You can also resize it down, to make it smaller
1.resize2fs
Smaller
-3g

2.fdisk
Shrink partition
D3
N3
3gb

^^ this is an old method that is obsolete

Logical Volume Management Lab5
Take your home directory and make is into a logical volume,

Sda
1
2
3
Make 4 – extended partition, inside four make 5 and 6

You can take sda5 and sda6
1g 2g ----physical partitions
You can combine them into one volume group, called Seneca. 1 VOLUME GROUP
Seneca Represents 3g cause its 1 and 2, now that youhave a

VG you can make Logical Partitions,

Make 3g home , how to make this larger you can throw another drive in, sdb1 and sdb2, partition it with fdisk, you can add sdab1 into Seneca, you can –add the physical partition in the volume group and extend home 10g, this is done live.

You can use the home (logical volume) as a partition.

Going over the Lab,

First command 5 6 unused
Physical volume create
Pvcreate

Volume group create

OPS435W7 Review

2007-10-17T06:58:00.000-07:00

OPS435 Review for Test 1

0090
1016

If you r a linux administrator, so you will have many tasks to perform and going, for instance we would be doing back ups when your doing a weekly backup what time would you choose to do the backup, middle of the night on the weekend, you use the chron deamon to schedule your job, three items to make this up chron d, it’s a utility that always runs in the background, it continuously going and looks for certain files, and if it finds any jobs ready to be executed it will process the job, the files names it looks into are called /etc/chrontab every user that allowed to use it has their own chron file,the chron deamon looks into top this how do you create one of the files, you use a command called chron tab, and is located /usr/bin/chrontab…..bin stands for binary, chron tab and chrontab file, this is the command you use to edit this file and once you have this file the crond looks into the file to get the jobs done, some of the other items associated to this is /var/spool/cron/allow, the admin is allowed to use the chrontab file, no one else is allowed to do that, but if the superuser wants to allow other people you go into the chrontab to add the users to use the file to do the jobs, theirs also another file called /var/spool/cron/deny this is your not allowed to do it, you can only use one of these files.

/etc/chrontab files contain the jobs,

The other files on the slide are used by the deamon,

How do you set up a job to be run, the information you put in the chron tab file, has to have a certain format, that’s how the deamon what you are suppose to do, this file contains 6 fields, minute, hour, date, month, day, command string, you can have the month in numerical or three letter format, small letters or capital letters or in cap followed by small, only in these three types

Day of the week, you again can specify it in numeric or text, it works like this, 0-6, 0=Sunday, some can be 0-7 which 7 can be Sunday, always use zero.

The last and 6th field is the command itself, what you want to do at that time, lets say we want to do a backup and we want it done at 2:38 on a Sunday morning, on the first 10th 20 and 30 of the month and the month is October, day of the week either Sat or Sun

38 2 10,20,30 10,OCT 6,Sun /bin/backup

Couple of special chars that are used in the chron tab file, lets say any month, how do you normal say everything, if you put a * where the month is it will be anything, another one is / its not a divider but a repeater.

Also lets say when you do any linux command stn output and stn error, you are going to be doing this 2:30 in the morning are you going ot be their no so you wouldn’t want it going on the screen, the default location, where would you like it to go, somewhere where you wanna see it immediately, stnout and stnerror goes to mail, so matter where you are you are going to get it by mail, if you want it to go somewhere else you redirect it to somewhere else, you redirect it from mail to go anywhere else. The default is mail.

• every minute of every hour of every month of every weekday
• * * * * * * who | grep ‘^evil ’

Run a script every odd hour
0 ½ * * 1-5 /home/bob/script

The chrong tab is created by the chrontab command if you execute this command
Chrontab
-e = edit
Take the contents of the file and put it in a vi buffer, by using vi you can makes changes if you don’t have it, it will open a new buffer in vi and you can enter in commands, and when you finish :wq once you do this, it will take a look at what you have done, and if any mistakes where their it will tell you line so and so and do you want to go back and edit, you say yes and you can go back and edit it. Only when u have everything correct it will accept it and save it in to the chron tab file

-r = delete or remove
-l = inside the file, list the contents of the file
-u [ username ]= only used by the super user can do anything to anything to anyone’s chron tab file

23-7/2
11 at night to 7 in the morning then
Every two after aftwareds

8 PAGES wrong, half multiple choice, 20 q for 20 marks

2nd part shell basics, it will contain, the 9 steps of the shell, all the special chars its looking for, you should know all the special chars of the shell interprets the one that we have covered also

Variables mix and matrch and do anything

Commands and utilities, do something then figure out what commands you put together to accomplish the objective,

Even a bonus, a couple,

The only difference between this, the other questions part marks, the bonus no part marks they work or not

Interpret the script run it and what you see on the screen.
For a total of 70 marks + 5 bonus marks

CUT –F 1-6 a*b* c?t

$0 – positional character, the file ur running
$? – exit status of last command
&& - if $? Is 0 then it is successful then go on
|| - other way around $? Is 1 then go on
“ $ ‘ \ “

\ = single character quote the char following me is not a special char
Echo ààà
Echo $(a) erroràà

Tr [A-Z] [a-z] | tr –d ‘.,’ > b

Tr “” “\n” < a

Tr “ “ “\n” < a |tail -2|head -1

Walk through keep track of all the variable contents, the vars will change, and if you don’t keep track you will loose what the values were, when you do walk through, in pencil and pen do all the variable contents as you go through each command and number 2 you have to know your commands, you will have to interpret the commands review commands and keep track of all the values,

OPS435W5

2007-10-17T06:56:00.000-07:00

We use the test command in anything we do, you can test for values and different conditions and decide if its successful then if its not you can do something else, for instance if you look at you rassignment when your doing verification, and even after wards you see if its this or this, or something else, you need the test command in order to test the conditions you are looking for, looking at the

Test Command

Test command test for vgalues how this value compares to this value,

A=3 B=5
Test $a = $b

Two operators the = compares values in their ASCII values

Symbol versus text,

This is where a lot mistakes are made

$?
2 – failed
0 – not successful
1 – successful

-o equals OR

-a and

[ $a –eq $b –o $a –lt 20 –a $b –le 0 ]

The and is done first before the or
Either this is true or this is true

Another version of the test command

[[ $a –eq ]]

The difference between [[]] and []

[[]] can use wild characters * ? ‘ ‘ can use any one of these, while the single brackets cannot

Flow charting to design a program, a map to get their, tell you what to do to accomplish ur project, it takes a large program and breaks it up into small pieces,

/dev/null the garbage bin of linux

Case will try to match patterns against the constants of the variable, the case statement will test for a string in pattern 1, you will have a pattern 1 it will try to match the pattern with the contents of the variable if its true then it will execute the commands under that pattern then it will go t esac (case spelled backwards, closes case) if it doesn’t matches it will go to the next patterns.

The case is looking for a special char wich its closing parenthesis

Case $var in

2[0-6]) ____________;;

T*)
;;

*)
;;

esac
Case can you file name expansion wild chars *? []

Matching 20 – 26 if it has a match it will match and go through the commands
2nd case T*
3rd case * .

How does the case statement know that it will end after the case stement an dyou have to tell it you must add ;;
\

Cat <<++

<< special meaning a hear document, they are saying we have a document that has data in it and the hear document says to the command here is your data, it allows you to provide data to the command inside the program, it can be provide within the program itself, by using a hear document,

you also have to tell the command where the document starts and where it ends, he has a ++ but it can be any pattern that you which, but what every you use you have to tell this is the end,

cat <<++

Main Menu
1. 232
2. 2.432
3. 453
4. Please enter your selection

++

Read banana

Any command at the top it don’t have to be a cat

x|X the pipe in the case statement is an or, you can check for multiple patterns it doesn’t have to be one pattern

case Zodiac sign, u can use it in the day of the week

OPS435 W4L2

2007-09-30T21:13:00.001-07:00

OPS435

Chinese year doesn’t start on January 1, calendar based on the lunar, ours on the solar, instead of making it difficult u can assume January 1st to December 31st, each year has an animal assigned to the year, that’s number two, the year they enter the proper animal number three you gotta tell the user what day of the week their born in number four how many days in the 21st century they have seen it starts January 1st 2001, they can give you it two ways

Age.bash and give you the birthday
They can also give you without a document,
Age.bash
The very first thing in your assignment is to find out the user entered data in the command line or not, if they didn’t enter data on the command, then you ask the user for the data, so you the data form the command line ro from the keyboard, depending on what, you must check it first, the messages on the script should be a standard error not a standard output, number 2 is, because no loops you don’t have to put it in a loop, stage 2 has to be in a loop, you must stay in the loop till the data is correct then you can come out in the loop and take the data, but stage 1 no loop, see if the data entered is eight chars long, if its not display message on sheet, check if they gave you a valid date, compare it with the cal command, check if its not a future date, and if it is you tell em what they entered.

The rest of it!

Calculate years and age in full months in instance if one of you

September 19 1990, today he is sixteen , must be a full year before your 17, same thing happens with months that’s why you must figure out months, for instance if you go from may 12 jun 12 full month, may 12 june 11 not a full month, that’s what he means by full months

No exit or clear command in the program, do not use the –p option with the read command,

Read –p message variable, what he is saying don’t use the –p option with the read command in this project, an example of what he wants exactly on the screen.

A couple of other things about the assignment, comments through out,

Another command we might use,
When you do calculations (()) heres a warning when you use the (()) not only does arthimetic expression, also checks to see if ur doing decimal or octal, if it does the octal will do octal calucations or decimal, the moment it sees a number with a zero its an octal number 07 + 09 u will get an error, octal 0-7 deciam l 0-9, the numbers ur using cannot start with a zero that way it sees its decimal so it will do decimal calculation.

Another command to do this (calculations)

Expr only does decimals if you say 7 + 09

Expr 7 + 09
With this command u must have it exactly the way it should be, lets say you want to multiply contents of variable A by 20 $a + 20 that will fail , + is a special char and go into correct directory and replace it with all the names, how do you prevent the shell from interpreting this you put a \ in front and it will work, and all the other operators apply to this command as well, this command does a lot as well, but only the arithmetic part of this command.

Cal 02 1971 | grep

Cal 02 1971 | grep –w 2

Test command checks things, coming week lots of stuff on

Conditional parameters

Date +%S time frame

The moment you hit the key board

January 1st 2001 until today

Cal –j how many days

Today is 2007 09 28

Lets say we have 2000 10 29

DCN386 W4L2

2007-09-30T21:12:00.001-07:00

DCN386

The more protocols you know the more money you make, 100’s Data Communication Protocols,

How do they figure out to do this that is why we got a hand out, the little hand out is talking about protocols in general its offereing you a template a frame work where we can understand protocols, we have a short list of 8-9 things theses what protocols do, lets say their 10 protocol questions you can use this to help you understand protocols, all protocols have rules, more then rules, all protocols, segment and reassemble data, lets say questions 1
How ip work?
Tell him how ip segment data
How tcp do?
How tcp segments data
What does Segments and reassemble?
Break it and put it apart

All data breaks into data, packets, frames, segments

Why do they do this?

These Error Control, think of two computers ….one computer has a file fu.txt you want to move it to one computer to the next, you can write a program put it in one file in giant message and send it, it would be stupid, why? Because of errors, take it and break it down into little Ethernet Segments data, if your sending it through the network card it will take the data and send frames and the maximum size is 1500 bytes, when data is receive at the destination each little segment must be put back together again, segmentation and reassembling, understand how much data is it sending, think why did they make the frame side so small, the likely hood of problems is good do they deliberately send, we are going to look at IP

IP was created in such a way it can send big frames up to 64000 thousand bytes, weird, lets move on

All protocols , the 100’s of datacom protocols they rely on the ability to work with other protocols for example TCP/IP that is two different protocols but must be used together on the internet, whwne a protocol uses another proctocol you would say the protocols is encapsulating the other protocol

It means on protocol is relying on a higher level protocol to operate this is an important thought, the osi model gives a briallant glimps of this protocol of encapsulation, briefly run over this

Computer 1 and Computer 2….connect them up.

Applications as tools that software uses, that start the process of moving data, lets say we \got together created using C++ our new brand new e-mail program, state ur e-mail can work with all the other programs its possible for a guy to send it on Mac to OS, how does this work, it works because e-mail programs use a appliucation layer standard X-400, X-500, email directory service 500, if we wrote an email called ERog our mail program will interact directly with the application program and we would put a little piece ofd data and infront of it indicate its an x400 identifying a piece of data, so far no encapsulation happened, e-mail programs going to pass it to the presentation, has code conversion, UNICODE, UNICODE most important standard in our futures imergins standarnd that will be used by all software producat over the world, some people that know Unicode will be valuable Unicode, now we use ASCII you can have 256 chars, UNICODE allows every language UNICODE will allow different languages, ASCII to Unicode conversions, we pass is down to the, presentation encapsulated the application layer, what happens next what is a sessions, your bank card, as soon as you put it in the bank machine you are initiating a session, first thing will send a signal to the banks head office, says some guy wants to start a session, now you get a session #, everything you do is recorded, they send it using lower layer protocols, they subtract 100 from your account and the machine will spit the money, what happens, you don’t get ur 100 bucks go into the branch talk to manager and u tell them your problem, the assistant manage will check the session layer software and see that u wanted 100 but u didn’t get it , sessions are kinda important, the point is session layer encapsulates to presentation layer which encapsulates the application layer, then passes it to the transport layer, there are transport layer software, TCP and VTAM, the purpose of the transport layer to organise the end to end transmission, and there is realiability, it provides reliability, think reliability, the point is it will encapsulate sessions layer stuff and infront of it will put TCP control information, then is passed down to the network layer software will encapsulate the TCP layer, give me an example of a network layer protocol, the INTERNET PROTOCOL, IP takes the entire tcp unit and encapsulate that unit and puts its own control information in the front, IP can take a packet of into and route it anywhere in the world, IP does not know how to get out of a computer, once its out it will bounce from router to router, doesn’t have the smarts to get out of your computer, so it passes down to the next layer IP packet, Ethernet does one thing allows data to escape from your computer and passes it would to the NIC card and NIC gets it out of the computer, it takes the entire ip packet and encapsulates it by putting Ethernet control information infront of the whole thing, the whole packet will make it to router, remember doing the lab connecting Ethernet between one workstation to the next , to encapsulate the ip PACKET AND PUT IT OT THE NETWORK, Encapsulation. All protocols work with other procotocols work with other called encapsulation, they use
CONNECTION Control what does this mean?

The Bank Network, Bank branch 2 bank machines, two look for 100 bucks and both type it and both his enter exactly the same time, because bank running SDP Synchrouns Data LINK SDLC uses a system called Pully so theirs no collision, does Ethernet have Connection Control, it has sort of connection, not that good, Ethernet connection control technique to examine the line if theirs no data then send it, but they can do it simultaneously, Ethernet connection control strategy is identify when collision happen and offer a solution to do this, Banking Networks never want mix ups, their to important so they use a different connection control

When you tell him about the protocols?

How serverl protocols handel connection control

All protocols think about wether or not to worry about delievery, SDLC will never have this problem it’s a datalinkprotocol, how every Network Protocols have to woorrry about delievery,

You run ip and ip breaks data into segments because all protocols into segments, send the little pieces into the internet, some pieces will go many different ways, how does IP put it together again to put it together, its going to remote them buffer

When you talk about a Network Layer Protocol?
Hwo does it gurentee ordered delivery, what is flow control

Flow control any attempt made by a datacom protocol that it is

When you buy routers, commercial routers you buy them and should be away how many packets persecond the router can handel,
Two routers, that can handel 5000 packets persecond, what we are going to buy three commercial router and buy 5000 packets persecond what if both router one and router two send 5000 packets persecond to router three, what ip solution to flow control?

Ip like Ethernet has sort of a strategy, it is to dump the packets period, IP is connetion less protocol, no flow control strategy then dumping packets, unreliable but we use it NO FLOW CONTROL HERE,

Error Control, Checking and Hendeling Error, we talking about CRC, most protocols almost all use this to test for Errors, this can happen it 2 3 4 layers, CRC is the most advanced way,

Other protocols will rather die then dump data, when looking at this how do they handel errors

Addressing, You send an e-mail out of computer, several,

Ip where does it look like where does it comfrom?

The only protocol with multiplexing is TCP and we will talk about this next week, remind TCP is a multiplexing protocol.

How does IP work??

What is IPs jjob?
All protocols have a job, IP has one job, to take tcp data and move it through a packet switch network at the highest speed possible, IP’s only job, TCP data, and pump it through a packet switch network

What is this packet switch?

Packets with network layer protocol, ip is one, IP is a packet switching protocol, Now if you met IP at a party it will introduce itself, Fast and Totally unreliable, for a protocol to be reliablt it has to do things like flow control and error checking, doesn’t do this cause it slows things down, it dumps packets, it does that because it wants to be fast, how does it work, header information,
IP has 20 bytes of control information in its header, when you want to understanding a protocol by examining control information in the header field cause that how it works

Lets look at the pieces of information

Version, its 4 bits long, 0100, identical, soon ull get an email from your isp[, and it will be ip version six, 0110, the version of ip…..

Header Length, 4 bits, for test one no options, don’t worry about these first two….

Type of Service, 8 bits, how old is ip, routers ignored TOS all of a sudden its become important, what changed on the net, VoIp, to make this possible routers have to allow priority to voice packets, as apose to data packets. QOS in TOS, the 8 bits allow routers to proritize different packets,

The way they work, data comes through the serial port, routers will temporarly store packets in memory, the first packet in will be the first packet sent it, now theirs a higher type of service value and will be send out first

Test 1, TOS can provide priority function, Routers use to more important data.

Total Length, Segmentation And Reassembly, 2 bytes, max size 64k big packet size, big segment size, most ip packets are smaller,

All protocols fragment data, IP can break it to 64k it still has to reassemble the data, because it makes an attempt at ordered delivery.
1.2
Routers hate big frames, ip builds big fram sends it out to router, ip the same software, also runs in routers, ip and router however will take the big frame and break it into pieces, break it into three pieces, heres the problem, only the first piece have the control into, takes three pieces and copies the header information, the receive computer has to know how to put them together, how it generates a random number 64k,

Identification Field , 16 bits, if a router breaks it into three, each piece will have the same identification, so a computer that receives packets knows these three packets thoug be joined together, but how to join em together, it doesn’t know the order, but it does routers, the put a value in each packets header called

Fragment Offset like a sequence number but not quite, it offsets, 0-1500, 1500-1500,1500-3000, computer puts it in memory, the first packet offset of 0 memory location 0, the 1500 packet third offset of 15000, place it in memory by offset value,

Router analyzes how it broke it up and the fragment offset, to put it all together in the, have a default value

MTU Maximum Transmission unit, mtu 1500 bytes, its default value, why do you think CISCO made it 1500, cisco realized all data will be broken up to 1500 bytes by Ethernet,

Flags, 3 bits only 2 used, one of the bits are intresting the middle bit if its zero that means, that 0 first 0 second 1 third last fragment.

Time to Live, The internet is a network of 100s 10000000000s routers they understand Source address and Destination address, how about if you put one that didn’t exist, a value is places in here 8bit from 0 to 255, default is used is 32 anywhere in the world default.

Protocol Field what higher level protocol is handeling , Two protocols UDP TCP , Network Layer, UDP data Ip knows by looking in the code3 to deliover the data to UDP,

Header Checksum, hold fashion name for CRC, error checking thing, does error checking not handling, this is all ip does as far as IP,

All left elobrate addressing scheme it offers, a Source Address and Destination Address and each 4 bytes long, each address, made by an network identifier and a machine

Network ID and Host ID

Subnetting an IP address,

DCN386 Great Site For Test 1

2007-09-27T06:48:00.000-07:00

Practical Guides . . .
Practical Guide to Analog Modems
Practical Guide to Frame Relay
Practical Guide to 56k
Practical Guide to Binary, Decimal and Hexadecimal Numbers

OPS435W4L1

2007-09-27T06:47:00.001-07:00

OPS435W4

Assignment #1 is up and running, what we need to do , last couple of weeks if we get a birthday date you can get the month year date out to do calculations and that’s all the assignment is about, write a script any user can run your script in two different ways, you create a file called age.bash and the user can provide you with your data in two different ways, one they put it on the command line as an argument, age.bash 19850330, or they can do it this way age.bash and no arguments, so in the first instance they are providing the data from the command line and the second they are not, there for the script must check to see if the user provided you with the data/argument, if they didn’t provide you the data you ask for it command to use to ask
Echo “YOUR DATA HERE”
Special command you use to capture data from the key board and that command is the

READ variable

So the variable name what ever name you assign to it that data will be automatically assigned to that variable, couple of examples later,

…once you have the data, and this applies to every program you write when communicating with users anytime you get data from the user you never use that data immediately you must verify it, if you try to use incorrect data you script will fail, FIRST VARIFY the data, once you ascertain the data is correct then you start using it not before, so we will see how you do this, your script for instance in two stages 1 and 2 the first stage and the submissions dates are different, stage 1 2 weeks stage 2 4 weeks, stage 1 verification of the data, first the we see the final result that should be displayed on the screen, all this is for stage two…..LETS LOOK AT STAGE 1

There are 5 steps you must go through
Step 1
The date is number 1

Determine they gave the data or not, if they have then you have the data if they did not provide you with the data on the command line then it is captured in the variable now you got to verify the data,

Step 2
Look at the data how long is it….is it 8 characters…….${} -this construct
If the eight chars are not their you got to tell
Then determine if their all numbers
Then check if the date is valid
We have to see through the cal date if its valid

Display feb 1989
U tell them what you entered and tell them its an invalid date, if the date it valid then you go check the last item to future date, you can have a user that hasn’t been born yet, if it is correct you have verified the data coming then parse it and do it for stage two

Lets see methods on how to do this, stage 1 should be inside a loop, if its incorrect you have to go back to top and verify from the begging stage one should be inside a loop data provided should be correct to get outtake the loop, for you u don’t have to have it on a loop. For our submission it’s a one shop deal, how do you know if they entered data on the command line…well you don’t yet so this is how its down.

Lecture Schedule Slides:
#! shbang
#  comment

Understanding parameters when you enter anything on the command line the shell captures everything that’s their, its captured, lets say we run are script and we have multiple arguments lets say

A b c d e ………… j k l

The moment you hit the return key the shell captures everything on the command line….special variables called predefined special variable…..what they are is this the command is age.bash it will automatically be assigned to a special variable called 0, remember variables and what chars you can use to assign names to

Variables = letters, underscore, numbers as long as their not in the first

If you want to see what is the name of the program what command will you use….

echo $0 it will automatically tell you the name of the programs, if you say

echo $1 the first arguments and so on

$10 and up don’t exist , some of the new shells can go beyond but not all

Beside $0-9 the rest of var

$@ expands into all the arguments ( abcde…..) (puts “ “)
$* same thing as all ( this doesn’t put “ “)
$# it will tell you how many arguments were entered in the command line
$? The exit status of the last command executed
$$ PID of the currect running shell
Ex: ls A? && echo banana
Goes into $? If it = 0 then its successful, and if its not 0 then its failed

$! PID of the last command executed in the background

These are the parameters need to know the love, and $0-9

The read command and how it works,

Read a
Sits and waits for it

Echo $a will show you what was entered

Read a b
Reads the first word then the last one captures the rest

You can use the read command for everything

Read –p print the text on the screen more then one word put it in quotes…..

Read –p “give me your birthday” a b d

Read –s silent….it doesn’t show on the screen you use for passwords

This is how you capture data from a user from the keyboard using the read command.

Readonly makes it so you can change the value of the variable………………….

Now the

If
then
else

the if statements executes the command what ever u place after the if statement, when it executes the command it goes to $? To see if the command is successful or not and if its successful it will go to the then or it will go to the else, fi  like end if. Simplest version if
If
Then
Fi

One command under command , else is optional.

Vi ass1

With the test command you can do checking of variable,
Test value1 value2

test $# != 0

if and a read command to see if it equals to zero.

Or you can do bd=$1 which will give you what was read from the command line, after the if statement echo the variable, run the program or script and see what happens

#!/bin/bash < tells the program where its run from shbang
You can use the test command under two different ments
[ $# = 0 ] ( testing the number of arguments equalling to zero ) && echo you did not enter any arguments on the command line && exit

Since we have entered four it will go to the next command the
More arg  display the contents of the script

When you run g a program the sub-shell will run your program, so when you did echo $$ in your script you showed the PID of the shell running your script.

Echo –e – interrupts backslash characters, the UNIX command uses \ to tell what to do the Linux version of echo does not recognize \ chars

Echo –n do not echo the new line character if you don’t wanna go to the next line this is linux, unix does it this way echo \c

-e linux command recognise the back slash characters then you can use \n to say enter a new line

While loop, simply how they work, just like the if statement if followed by command while followed by a command and the while statement will check the $? Of that command to see if its successful or not, and if it successful it will execute between the do and the done, and from the done it will go back to the while, if it is it will go through the loop again

Is 11 not equal to 44

[ $1 –ne 44 ]

SHIFT – how it works, will shift the arguments the variable $1 through $9 once to the left, what will happened $2 into $1 the contents of $1 goes into the garbage bin its gone, what happens if we did
Shift 2 ---- shift twice to the left,

Find the programs in public, programs are arg and args

Echo –n new line take out
Or construct with the braces try and use that one

BREAK

Command we already know the
Grep command use a number of different options,

Grep pattern data

We will look at regular expression do the same thing for data rather then file names , similar chars with meanings, the grep command is the one that interprets the regular expression, it’s the command itself that does the interpretation of regular expression, when your using a pattern use a ‘ ‘ if you don’t have a special char the ‘’ are doing nothing the ‘’ tell the shell don’t touch this pass it on the command to interpret, if you had a char in their this is not a special char.

Grep searching for a pattern in a database and when it finds it what does it do, it displays the whole line you found the match in

Cal 05 1887|grep F

Number of options with this command, how do you display only the line that has 2 as a full word and not part of a pattern?

Cal 05 1887|grep –w 1

-w word only
-i ignore case
-q quiet
-E
grep and xtended grep, it can use regular exp and also you xtended reg xpression, regular grep search for one patter, x multi patters, if you wanted to use xtended grep egrep or grep –E

-c count of number of lines matched
-v all lines that do not match the patte

DAT702 W4L1

2007-09-25T15:22:00.000-07:00

DAT702

create table marvin select * from grades;
copies new table, does not copy constraint
create table marcin2 select grades,stunum,code
create table marvin3 select * from grades where 1 = 1
create marvin three and get the same thing where this is very usefull as we create marvin4
1= 21 this will copy an empty table, but its the same table.

“We just did table copy” ExamHint -table alias will be important

Select What about the repeated names” AnotherExamHint

In lab 3 like a list of the same students as the first name of all the other students were lookinga the students that have the same first name as the other students, think of ur students table, somewhere you have mary and another mary somewhere else at the table, databases process one record at a time, how will it process those two, we are going to deal with this but dealing with one table it will not work, the way we do this, back to the things we talk about before,

Select * from students,students; < Cartesian product when no where clause,

If the students table at 40 record cheat give table alias
Select * from students s1,students s2; < Cartesian product

We are going to only show certain things

Select s1.firstname,s1.lastname,s2.firstname,s2.lastname from students s1.students s2 where s1.firstname = s2.firstname and s1.stunum <> s2.stunum;

Select distinct s1.firstname,s1,lastname,s2.firstname,s2.lastname from students s1.students s2 where s1.firstname = s2.firstname and s1.stunum <> s2.stunum order by s1.firstname;

^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
Needed

Select “Another example of a join” AnotherHInt;

Select * from grades where code = “hwd101”:

Select stunum. From grades where code = “hwd101”;

Select * from grades g1,grades g2 where g1.code = “hwd101” and g2.code = “ops200”;

Select distinct g1.stunum from grades g1,grades g2 where g1.code = “hwd101” and g2.code = “ops200”;

Select “ Now the easy way” ExamHint;

Select * from student innter join grades on students.stunum = grades.stunum;

If we rewrite and put left join it will show a bunch of people with null

Inner join takes students and student number , left joins is finding the Nulls, if we want to make it nicer you isolate the nulls and do a where clause

Where Grades.code is null

Select “Now the other way” examexam;

Select stunum from grades; 1 column 1 field, every one took a course, its one field,

Select * from students where stunum not in (select stunum from grades);
All people that didn’t take the course, called a sub query

Select * code from grades where stunum in (Select max(grade)from grades where code = “HWD101” and grade in (select max(grade) from grades where code = “hwd101”));

In brackeys sub query, back to front

Select max(grade)from grades where code = “HWD101” and grade in (select max(grade) from grades where code = “hwd101”);

Select students.* from students, grades
Where students.stunum = grades.stunum and grades.code in
(select code from grades where stunum in
(select stunum from grades where code = “hwd101” and grade in
(select max(grades) from grades where code = “hwd101”)));

^^^^end of sql this end of mysql, writing queries, in most term test do something with a left join and a sub query, run a practical test on Thursday,

Want to know everybody who taken ops400 and hwd101

Select stunum from grades where code = “ops400” and stunum in
(Select stunum from grades where code = “HWD101”);

^^^^^^runs is twice did a sub query that took one of courses, runs it again finds the ops400 now it knows each one of those took ops400 and 101

Select * from students where stunum in
(Select stunum from grades where code = “ops400” and stunum in
(Select stunum from grades where code = “HWD101”));

^^^^^^^^^^Shows the whole table

Practical test based on lab four

OPS335 W4L1

2007-09-25T14:30:00.000-07:00

OPS335 FREEEEEE^^^^^^^^^^^^^^^^^^^^^

Confusing about the hard drive layout, if he shows us pictures of sector 0 which is the first sector on the drive, sector 0 is going to be the MBR, after that you have the first partition so you have partition number 1 it’s a whole bunch of sectors it be at least one cylinder well the first partition is the 1st sector of the 1st partition, so if he said for example, lets say sda if he says dd if=sda then sda is going to be the mbr if sda1, then you will be getting the 1st sector of the 1st partition, and pretend we have portions number 2 this is the first sector of the second partition, so sda2 then your copying another sector and not the 1, the MBR is bootable that’s when you do the file command it’s a bootable file, the other sda1 and sda2 are not bootable cause they are second in command, but always the mbr is first if you file one of mbr it will just say data. Mymbr 512 bytes

Df look at whats on ram
Fdisk –l look hat the partitions

Ls / is the ram only system

Mount /dev/sda2 /mnt

Find /john –name menu.lst

Updatedb – updates whole database

So we went over how linx boots

POST
BIOS –activates code, program comes with the main board. Grabs MBR
MBR – LILO or GRUB NTLDR any loader you want then executes in memory reads the Kernel and initial ram disk

Initial ram disk file holds drivers that the kernels needs to mount the fs
Kernel – probes all your hardware, on your main board there are hardware ports for many different busses, each port has an address and all the kernel does when its booting up it sends a messages to all the buses then all the ports on the busses, asking is their anything their, 18 PCI if theirs nothing their in micro second the kernel says theirs nothing their, if it sends to you network card it will send a string back, the name of the piece of hardware, network card made by intel…..

Then is mounts the root file system then it mounts it then inside the root file system it finds the init program and init looks inside /etc/inittab, and from here it knows the run level…7 diff run levels after init it calls rc, small name for a important programs now that is knows the run level it will go to directory that is called rc3.d it will go into that directory and all of the scripts that start with a capital s will run them in numerical order, each one represents a sub-system …a start up of a sub-system.

When you see fedora or suse then it says done every of the green lines is one script finished it’s the script that writes that line out that means its done. FAILED, STARTED, u know which is working or not, …

Run level 3, its multi-user with network, run level three ill let everyone log ssh, ftp. In the dir /etc/init.d this is the scripts of all the sub-systems in the computer, if you did not install sh server the script would not be their. The important thing to note the scripts are used for start up and for shutdown, if you want to start up the sshd server you use the same scripts, how does it know what to do by the link name capital S or K, when it calls the script and it begines with a S its starting and with a K shutting down, so where are these scripts > rc3.d their all links some are capital S and some capital K and each are al ink to the other scripts ls –l S09sshd it linked to sshd this is the start up script to start the SSH server,

Run level 5 graphics multi-user network

Ps ax | grep sshd

What ever service ur running u will have the actual program and also a start up and shutdown script,

Carpald – server
Carpal – start and shut down script

telnet 3 drops you to run level three, it will run all the shutdown scripts for 5 and start up for 3, better then doing a reboot,

wall write to call
ln – link
chkconfig

init telinit
ls is a user process
how is a daemon different

Phase synchronization

2007-09-25T06:18:00.000-07:00

Phase synchronization is the process by which two or more cyclic signals tend to oscillate with a repeating sequence of relative phase angles.

Phase synchronisation is usually applied to two waveforms of the same frequency with identical phase angles with each cycle. However it can be applied if there is an integer relationship of frequency, such that the cyclic signals share a repeating sequence of phase angles over consecutive cycles. These integer relationships are the so called Arnold Tongues which follow from bifurcation of the circle map.

One example of phase synchronization of multiple oscillators can be seen in the behavior of Southeast Asian fireflies. At dusk, the flies begin to flash periodically with random phases and a gaussian distribution of native frequencies. As night falls, the flies, sensitive to one another's behavior, begin to synchronize their flashing. After some time all the fireflies within a given tree (or even larger area) will begin to flash simultaneously in a burst.

Thinking of the fireflies as biological oscillators, we can define the phase to be 0° during the flash and +-180° exactly halfway until the next flash. Thus, when they begin to flash in unison, they synchronize in phase.

http://en.wikipedia.org/wiki/Phase_synchronization

Acoustic Coupler......way back...Half/Full Duplex DCN386

2007-09-23T16:20:00.000-07:00

Personal fav….pin 22, think about a computer using a modem to contact another modem, how does a computer working with a modem know how to make a phone call, essentially this I what you do make a phone call to send data, …reminisce BNS got this new tech, mainframe comp and they had a telephone and fit into a device attached to a computer, u pick up the phone and heard this noise and put it to the ……acoustic coupler, a company called haze who made acoustic couplers, though themselves why not put a computer chip that can recognize basic basic commands… and they did, they invented the modern modem, 70% of people today, they will discover two things they are using RS-232 they are using Haze Compatible instructions<-- all the rage, haze instructions all start with AT what happens OS software in ur computer understands haze commands if you try to call someone it will send a attention command to ur modem, you want to modem to dial

AT [D]pulse1231321

Something called tone dialling and pulse dialling, lets say u wants pulse the os in the software in the old days you had to install the isp number the modem will recognize the above and the modem will send out a ringing sound to the DCE and the dce hears the ring ring sounds the modem has to ask the computer if its ok to answer the sound, the modem actually asked if it was ok to answer an incoming call, it will do so through
PIN22 ring control

It will signal down DTR, and it will know to answer the phone, if you were an isp then you would be great cause you want to answer incoming calls as fast as possible cause the isp always wanted auto answer, some modem automatically answer ATA

How many functions do we got,
that the half duplex, for the 70% people of the world still using modems its no longer half duplex, no phone company offers half duplex any more everything is full-duplex, what is full-duplex, send and receive at the same time.

Theirs is flow control one of the great instincts of control data is getting to the destination with out loosing data and getting their error free

Any activity that prevents the loss of data ----FLOW CONTROL

Look at this your ISP is sending stuff to you stuff is going to the modem, the way file transer programs work, data set through the serial port and they are stored in memory the os knows that the computer memory is getting used up sooner or later, pretend you want to download a file and write to ur floppy disk…floppies are slow…sooner or later the memory is getting used up and needs to write to disk, what happens to incoming data, it could get lost Rs-232….Request to send and Control send to flow control the data, if the computer knows not to send data it will stop sending pulses request send, the modem now goes it will not send data and will send signals the other modems to stop sending data, now that the floppy writing has finished it will then tell its okay to send, if the modem detects the line is busy it can send signals using clear to send, ……request send clear to send is used to flow control purpose/--this is what we have to tell him

Look on the internet RS-232 despite the fact is has their RS-232 Tutorial, no more physical layer stuff …Analog and Digital physical layer considerations Multiplex Interfaces physical layer…..start talking about protocols….cause we love protocols

First protocol we are going to talk about IP we will talk about IP next Friday, what we are talking about now is our first opportunity to get some marks, which will be next week, at least three marks, three percent of the course marks can be gained next week if you can go to back it has two configurations

R1 has a config
R2 has a config

You simplay type in the config for both routers hook the routers up rogether using serial cables S1 S0 hand also hook up a work station to the Ethernet port of the routers if he can ping form one to the other your up three percent.

What you do when your doing a config, you provide an ip addresss to that serial interfaces you provide the ip address to both Ethernet ports, what is an IP address,

Where do they com from, IP 4 bits long , they have to be unique, there are different classes, and the ip address is two address one the network and the other part identifies the computer on that network. Theirs millions of networks in the world, Seneca college has dozens of networks. Each network has a network identifier and a component that identifies the computer in the network

What are the class? Why were the classes developed, it was an accident, back in the beginning of the internet when their was a few organizations using this, if you examine the fundamental protocols the internet uses, its actually tremendously inefficient, the guys who invented ip were computer programmers they decided arbitrarily to have a 4 byte address, they decided to use the 1st byte to be a network identifier because about a dozen people on the network, they reserved these bits, the other were all host bits, on individual networks, Network one would be 0000001, 00000010, 4 the internet grew, 256 networks, they sat down and said lets change this lets make the old way class way, but have a new scheme have a range of addresses, and make B

0-127 A

B 1000000 - 128
1011111 – 191
Host 64 k

IEEE class C
1100000 - 192
1101111 – 223\

255-32

Static ip in the work station

Subnetting, why do we have subnets?

RS-232 ACHEW!~ STICK DCN386

2007-09-22T20:01:00.000-07:00

BREAK

One questions you can answer in point form sentences, the one question you can answer is RS-232 , now RS-232 to us is an unknown factor,

When he was our age rs-232 was the most important thing in the universe, in the 60’s RS-232 is a modem interface, an interface is, when you have two different technologies working together you require an interface,

Now when he was small computer where new modems were new, they were two different technologies inter-phasing,
The EIA standards groups started the RS-232 interface, first we must know it was bad, it was based on technology in the 60’s which is terrible, but the thing RS-232 its still around, remember 70% people of the world are still using modems, when they go buy this it will say RS-232, even know the
EIA have developed dozens very very good interfaces and RS-232 is still around, RS-232 is a set of instructions that allows computer to talk to its own modem, …..drawing of a computer a
DTE, to a DCE ur computer is attached to a serial cable to your own modem, down the serial cable signals can be sent both ways, the second thing you must know about RS-232 is it was developed in the 60’s data communications was in its infancy and the world was using something,
half duplex transmission an ancient system computer sends data and a computer receive data but not at the same time, modems attached to ur phone data you can transmits and receive data but not at the same time…

…lets look at the interface as it once existed a computer wants to send data, we want to send 0100001 A to another computer the interface working with the os will do the following, find a modem a little thing with a thick cable and if u cut the cable u will see how many wires are inside….when RS-232 was developed, …look at ur serial port even today they still have a serial port in the beginning their was
25 functions…..in a serial cable RS-232 has 25 functions at 25 functions because even though RS-232 can handle Asynchronous trans or Sync transmission, RS-232 is older then PC’s

IBM is in manufacturing PCz, which recognized all PCz will be Asynchronous, if a PC is going to be Asynchronous we don’t need 25 functions we only need 9 functions, RS-232 can do Async and Sync if it’s a = 9 S =25, each wire in the serial cable represents one function, k we want to send the A
INT14 data sends to the UART but the UART cant simply send the data, the UART asks how does it know if its being used by the new computer, first the UART sends a signal down one of the wire in the serial cable
….request to send, RTS pin2 in your serial port if your modem receives your signal in pin2 it know your modem has made a request to send data, what does the modem do, it looks at the phone line if the phone line is idle then the modem sends a signal back to pin 3, pin 3 clear to send….then modem also down the wire a carrier wave, that means the opposing modem cannot send data cause the current modem is sending data, it issues a …….clear to send CTS, then the modem sends the data another little wire in the modem called transmit data, even though RS-232 can have 9 or 25 functions only functions are used for data the remaining functions are all about controlling the data, sends the data down the pins to receive, transmit, send data,

rts cts

Now a modem is a separate device from a computer, when ur grand mama hade a modem she probably had an internal modem, how does the modem know it is turned down, what happens how would the modem know, it knows but the RS-232, one of the functions is used as soon as you turn on a modem the modem sends digital pulses to the computer …..Data Set Ready, DSR, the computer knows its on cause it sends down Data Set Ready, Data set is what we cal it…not modem….the computer now knows its turned one conversely how does the computer know the modem is turned on it does
……Data Terminal Ready, and they can start to communicate,

How many functions we got? 6.

Rogers vs Simpatico ----MUXXXXXX STATTTT DCN386

2007-09-21T22:55:00.000-07:00

He is going to use the same test as in the spring, we will continue on with the theme of multiplexing we talking about stat mux and t1 mux we are going deeper into the world of multiplexing, picture Rogers Cable head office it has four satellites on the top of its roof that put out ur cable signal, today we are going to be talking about Rogers modems how their good and bad, when you watch TV you are watching a mux signal, when people make tv programs CBC CTV and DIC, people make program say CBC, if CBC would like to transmit this signal through our cable lines they must send it to Rogers so he can put that tv programs on our tv through our coaxial cables, it just so happens for high speed video like your tv, you require to send a signal that’s six million hz, got it, that’s a lot of hz CTV wants to make a program and dic must send it all at six million hz they send it using satellites, now Rogers, has put coaxial cable throughout Toronto 100s of kilo coaxial cables come in many grades, thick copper wire, by insulatiord surrounded by wire mesh very expensive. Coax has incredible bandwidth…means high range of frequency, what coax cable can handle? Coax cable can easily carry 600mil hz, accounts for the fact you can get approximately 100 tv stations,
How does this work? 100 programs coming one wire all at the same time.
How do they not interfere with each other, how come….multiplexing….

CBC 600mil hz Rogers feeds it into the multiplexor, each send it so

CBC 0-6 CTV 6-12 DIC 12-18

All simultaneously down you cable, because of the frequency range they will not interfere with each other, ur remote will change to the channel and filter out every thing

What is this to do with data com…nothing except Rogers cable have offered high speed internet connection what they have done is reserved 1 600million hz channel for you to use for data, they give you ur little modem attach it to your computer and ur computer has access to 6mil hz, think about it 70% people in the world are using ordinary modems and those modems can handle 4000hz and they can achieve speeds up to 50000bps think about this 500000bps out of 4000hz think about wat you can achieve with 6mill hz, cause ur using coax this is available to you, using QAM, rogers can provide ULTRA high bandwidth at ur disposable, but the shit thing you share the coaxial cable, Rogers ultimately will be a victim of their own success, the more customers the slower the service will become.

Simpatico 4000hz, from your phone line how is it possible to get high speed down this?

They attached tthis a local loop, twisted pair cable, when you talk on the phone its an analog signal, which travels down the local loop to the phone company, you use 4000hz, how is this possible, what happens? U will see very thin copper wire, but even thin phone line, very thin copper wire, is theoretically cable , not only 4000hz but up to 1 mill hz, think copper wire is capable of this so why do phones not use that…cause it’s not necessary, what happens when you get simpatico, a bell technicians disconnects you phone line from the existing phone line network, she reconnects you not to an ordinary voice switch but to a new switch a DSL switch the DSL switch sends an receives up to a million hz, what do you do? You replace your modem with another device which bell engineers call a DSL modem but its not a modem it’s a digital device, now attached to a dsl switch….the dsl switch takes the million hz and breaks that million hz into three different transmission bandwidths, dsl is a mux service just like Rogers, when they send tv and data signals, broken up to three discrete bandwidths,

0-4000hz ---- first band width is (dsl modem) the phone attaches to the dsl modem so for voice the old traditional bandwidth is maintained signals going down ur dsl modem it is reserved for additional phone services, why didn’t they increase this cause its pointless…..when the DSL switch notices the signals, it simply transmits those signals to the ordinary voice switch. You need filters to filter out everything over 4000hz,

4K-1mhz – the dsl modem reserves 4k and approximately, this is for out bound data
100,000hz – 1m hz – in coming data

Why did the DSL designers do this?
Download faster, they know the internet user submits a little, but you get a ton of data in return, this is called

Asynchronous
ADSL

Sychronous
SDSL – bandwidth split between incoming and outgoing….

DSL is still an emerging technology going to get faster faster, in the states they have this already sounds amazing but their a problems, Rogers has a problem and simpatico has a problem…..Distance….the higher a frequency the more power you can send it, it’s a factory of life, the higher the frequency the more power it needs, attenuation happens, if you are a happy simpatico user and you live right next store to you bell office you are getting incredible internet connection, if you have a sensitive, you can literally see every step you take from your phone company the frequency becomes less recognizable that there is a maximum limit your phone line can be, theirs a part of silicon valley, they cant get high speed DSL cause its far from the phone wire, 18,000 feet is the maximum distance, you can see why doesn’t bell install amplifiers, expense, Nobody is sharing ur phone line like Rogers, ur phone line is urs, because phone system was designed for lower power operation the frequency is high and attenuation level is high, distance is the enemy of the happy cable user, the DSL switch is so intelligent it can determine the level of operation and it will deliberately slow down if the DSL modem recognizes the signal is weak, which means slow speed.

Rogers is a three mark questions
DSL is a three mark questions,

Economics - ECN550 GEN

2007-09-19T19:39:00.001-07:00

DOWNLOAD BLEACH!

Quiz Review

Get the most for the least
Supply = production
Demand = ppl want it
Price vs Quantity

Rule #1 Cost goes up, conssumers want less and producers make more
Rule #2 things work themseleves out in the end...equilibrium

We act to max our utility(happiness)

Homoeconomics - we all go for our utility(we are all jerks)

DMU- Dminishing Marginal utility the more the worse off we become....beer ruel

OC- Opportunity cost - what you must give up to get something

Marginal Cost - Devisions that are made at the margin

Economic Efficiency - get the right amount

Backbending Curve - Working more reach efficient sum, take days off to spend it.

Bartering - come to an agreement

Incentives matters --tax cheating

4% GDP - Gross Domestic Product - all goosta and services produced in a given year
GDP = CIGS
CIGS - Consumption, INvestment, Guv, Import - Xport

Make Money - wages interest profits rent

Everything in must go out

The circular flow -- people guv firms

Recession - two consecative quarters of negative growth....its a contraction

GNP - Production of Canadians
GDP - Production of Canada

<2% Inflation - the value of money decrease

Human Capital
Physical Capital
Technology
Natural Capital

Production POssibility Curve.....

This will be updated when done done

DCN386 Questions From W1&W2

2007-09-18T19:31:00.000-07:00

1. Can you send data through a vaccuume?
2. What is Token Ring?
3. What do protocols do?
4. How do protocols work?
5. Identify four standard making groups, what did they do or are doing?
6. What is analog transmission and how does it work?
7. Why is digital good and analoag is not?
8. What is amplitude, frequency and phase change?
9. What is digital teachnology and how does it work?
10. Why do signals diminish?
11. Why did the world go digital?
12. What is Ethernet and how does it work?
13. What is T1 Mux?
14. What is Stat Mux?

OPS435 W3

2007-09-18T19:28:00.001-07:00

OPS435W3
& - when you want to run any command or program in the background,

Foreground which u are running, running a program in the background you can have control while the foreground no

&& - com && com2 checks to see if the first command is successful then execute the second command.

Who | grep username

Com1 || com2 - || - not successful then execute this command

|| && is similar to if and else

Ls, who, pwd > f1

Use ( ) around commands that means you are grouping them together.

$(com1;com2) command substitution

(( )) – arithmetic expression – this is how the shell does arithmetic, this is used, for a couple of diff things, one arithmetic, also use the command to assign the results of a arithimitic function to a variable.

First put this a = 3 b=5
((c=b*a)) shows output

$((c=a*b)) shows standard output

echo $((a + $b*2))
u can use
+
-
*
%(remainder)
**(power of)
/
The shell does not care if it’s a variable name in this case when you don’t put the dollar sign infront it treats it as a variable name, this is a arithmetic command, everything inside it has to be numbers, since the shell knows, the moment it encounters text it says this must be a variable and replaces the variable name with the context, the shell automatically knows this, u may use it or not.

Echo $(( a**3 +b*6/3-1))

Display the remainder, this command is an integer number.

This week,

>> append
> replace

Pattern matching file name expansion,

Understanding Expansion

Echo Jim$d
JimBrown
Echo $dJim
Blank(nothing) no variable dJim

Echo {$d}Jim --use braces
{Brown}Jim

Appends the variable name within braces, leads us to the next item the braces can be used in many different forms to achieve many things
${var:offset:length}

This lets you cut poriotions of data from a file, we used cat for a variable and a file, this is a better way of doing it

Bd=19871223

Echo ${bd:0:4}

Echo my birth year is ${bd:0:4}

echo "The month of my birth is" ${bd:4:2}

Assignment will require you to do the following write s script anyone can use, the script will ask the user to enter the birthdate in the yyyymmdd and u take their birthday and tell them how many years month zodiac sign, Chinese anymore sign is, you are going to be using these formants and be doing all kinds of calculations to come up with the results.

Another thing you need to do , listen to this applies to every system, the following will apply, any time you ask the user for data, you never start using that data unless you verify it.

Before you start cutting out stuff u must verify the data is correct, so number one how many char do you except this data to be…8.... they have to be all numbers…check the date is valid.

This will tell u how many chars the data of a var contains,

Echo ${#bd}
# - tells you the

Echo puts a new line char at the end so you will get the wrong character, if you use the construct we have previously use it will be more correct,

Cover unique

Uniq unique

Sort unique | uniq -Cuts out the lines in ascending order

Uniq –d gives you the duplicate lines
Uniq –c – count how many lines exist in that data file

Cheat Sheet
Half a page of what you want, hand written.

Tr – translate, what this does it translates chars to this to this,

Tr abc 123 < galileo.txt

< input redirection

Every a = 1 b = 2 c=3

Tr ‘a-m0-4’ ‘n-z5-9’ Galileo.txt

All the capital letters will not be touched, the small letters will, pretend u have a file, u can change the data, so even if they get hold of the file its meaningless,

Tr ‘a-mA-M0-4n-zH-Z5-9’ ‘n-zN-Z5-9a-mH-M0-4’ < Galileo.txt > junk

Tr –d ‘%./.,fda?’ Galileo.txt
Deletes all the characters

That’s ur tr translate

The Find command,
Find [directory to search in] goes through every sub through that directory
Find .

Specify a search with specific items that have to be matched, for a file name,

Find . –name nameoffile

Find command does expansion not the shell, the find command can use regular expansion char, many capabilities, prevent the shell from interpreting f1* how do you prevent the shell, a backslash, single quotes, double quotes

Find . –name “name*” -type f –perm 600 –mtime 10 –exec rm –I {} \;

Type file, permissions 600, or greater 600 u put a +600, a minus for less in front of the 600

Also these files have to be more then ten days old in other words last time their were changed, they have to be ten days ago or more

-mtime 10 tend days +10 greater then 10 days, the find command has to match eatch and every one of them before it matches that file. Another one, -exec another command, rm –I interactively, {} represetnts standard output of the find command, ill show the full path will be redirecting into the braces, its going to delete all those files but first ask you, because its exec the find command it has to know where it ends, looking for ; to see where it ends but is that a special char to the shell ;, you don’t it to interpret as its own so you have a back slash.

Linux administrator on the weekend last Sunday you did a backup what you did u used a utility called backup, /bin/backup, tonight 3am you wanna do another back up a partial backup, you want to back up any files that have changed since the last backup.
Touch ts
Find

Chron utility to specify time sequence, this command will reside in a special file that the chron deamon looks at

Find / –newer ts –exec /bin/backup {} \;

Backup all new files

Multiplexing MUX T1 & Stat --DCN386--

2007-09-17T16:23:00.000-07:00

Why did the Ethernet guys pick a block size of 1500?
Token Ring and Ethernet
Token ring 64000bytes, why was this rule their, Why did IBM HAVE A BIG BLOCK SIZE?, have this in the back of your mind, why is it this?
Ethernet knew that every machine on a bus network will transfer data, and they will send it at the same time when they do it will be lost, if your designing a protocol so after theirs not a lot of collisions, there for if there is no data collisions you transfer bigger blocks…which would be Token Ring...

Why did it disappear?

Datacome situation you have not heard about this before, multiplexing, simple concept, means how does a device take multiple inputs, and transmit in one physical light, lots of ways of doing this, televisions signals are multiplex signals, or sympatico, you use multiplexing, Rogers is using the existing multiplexing signals the tv use……telephone gets mingled with other peoples voices …multiplexing.

This is data signals, if you got digital info that was once multiplexed, talk about time division multiplexing, TDM, we do this for money, this allows datacom people to transfer through one visible line multiple signals.

Leased Digital Lines come as low as
24000
48000
96000
640000

T1 1.54MBPS

96000  most common line speed, because in the bank branch is all text.

Pretend we are sending 24000, then we had a device a MUX and MUX at head office, you save money,

Time Division Multiplexer, next week, statistical multiplexer, the MUX reads one char from the input port and build a FRAME of data, every signal is 4000$ so if you MUX 9600kps you save only $500, you save a little bit,
He wants to hear about these on the test

Statistical MUX (Stat MUX) and how you can save a fortune, you can make a fortune

, know more about them the second one is the T1 MUX, a huge investment.

T1 MUX standard digital line speed 1.54bps, T1 Laid down by phone companies LONG time ago, now their laying fibre-optics replacing old digital copper wire NICs, T1 leased to co-operations. Why do companies invest money in these, long distance without the T1 MUX,

PBS – Private Bank Exchange how little offices hook up their phones

U hook up the phones and the computer to the T1 MUX works like a time division MUX, except you can have dozens of input lines, 24 phone calls to one T1 MUX 1.53, take 8 bits from each input port and build a frame, each frame 192bits, 8 bits x 24, at the end of 192 bits it puts a extra bit , separating bits, that was fine for voice, T1 are integrating these things with computer work so now its just data,

OPS335 Week 3 Third Lecture

2007-09-17T16:16:00.000-07:00

OPS335
Week 3 Lecture 3

Last week review, we talked about harddrive, know what a sector, cylinder, head, calculate capacities, fdisk to partition the drive,

This week more detail about the booting,
• We began discussions on Linux boot up.
1. PC is turned on.
2. POST
3. ROM boot loader loads MBR code.
4. Code in MBR loads Linux kernel and initial ramdisk ( DRIVERS NEEDED BEFORE MOUNTING THE ROOT FILE SYSTEM)
If its ext3 you need a ext3 driver, once the root fs is mounted, before this you don’t have any drivers, you need some kind of a driver to mount the root fs, its small file and is brought in like the kernel the rbm code, the kernel has the basic drivers it needs to load the whole file system, one its done.
5. Kernel runs and does hardware detection(1st thing it does)
All devices accessible to I/O ports, when the kernel boots it will tell u all the things you have on your system, the kernel starts the init program, which starts all the services in your system.
6. Kernel mounts root file system. Driver in the camera be in here
Thousands of drivers on the FC7 DvD, now it has access.
7. init program runs (process ID=1). <-- First thing it runs PID
Init has no parent PID id, every other program has it plus a PPID,
8. init reads /etc/inittab and determines runlevel(state of the computer) (0-6).
7 run levels, 0 – halt, networking continues to work at level 0, RL 3 Multi-user Networking, RL 5 same as 3, but with graphics, . INIT TAB the init table tells us what init we want to go to. 5 Full Multi-user with networking and graphics. 1 is single user no network.
9. init calls the rc script. \
rc is a bash script, run command, this script is the one that calls all the scripts for all the subscripts, init calls rc, and rc calls all the scripts for all the subsystem.

/etc/rc.d, all start up scripts for you computer, /etc/rc.d/rc3.d> is for run level 3. Start and Kill.
10. rc executes startup scripts (/etc/rc.d).
11. System reaches desired runlevel.

Ps –ax all processes running
Ps –al long listing
More then one program occupying ram at the same time. All processes are in a tree,

tree ps -a /

Manage your process
Signal PID
Kill -9 4010
-9 is a hard kill
more /proc/cpuinfo
every program is run for mili second.
280,600,000,000,000
3.14159265^2

Lab#2 Focous on booting up the system
GRUB, Grand Unified Boot MANAGER (Loader)
LILO, Linux Loader
We are going to try both, lilo is old grub is new.
Linux kernel is on the fs /boot/vmlinux-2.6-22 the kernel itself is sitting on the fs, it could be ext2/ext3 , reiserfs , in order for the MBR to load the kernel, so the code in the MBR, we have to tell LILO where this file is ahead of time, which sector, when the LILO code tries to load in the kernel it will know the kernel starts at 1321, the lilo code will go out to sector and bring in the linux kernel, LILO does not know about fs,

What is a file system?
A file system is a filing system, there are different ones ext2, ext3, reiserfs all file-ing systems prepare the hard drive, to hold files differently, LILO itself does not care how its organizes he told LILO to start counting the files on the left and when you get to the physical sector it has to know where to go, somehow before we boot the system we have to install LILO we install lilo we put the LILO code in the MBR, along with the code you put the sector where the kernel is and the initial ram disk file.
Ls /boot, Z means its compress vmlinuz…read while its small and uncompress it in RAM more efficient way. For every kernel it has a corresponding initial RAM disk, this must be read by the drive by the LILO program. Four and half mb has to be loaded in by the boot loader..

In order to write the code to mbr we use the command lilo, /etc/lilo.conf the conf tells lilo where the kernel in ram disk is, once it knows this it figures out the sector, and writes the sector in the MBR, so when you boot you system you know where it is. What we do is we modify the file to suite our own needs.

Original MBR contains the GRUB code, the program when we save it is GRUB.

/mnt/sysimage
/etc/lilo.conf

Synchronous --In Todays World-- DCN386 Week2

2007-09-15T20:47:00.001-07:00

How did they change the computer to a asynchronous to synchronous to achieve this is a personal computer your forced to invest into a NIC card, this allows the pc to transmit data, in a synchronous <-= sends big blocks of data, synchronous transmission, the NIC card is the machine that is installed into your computer to allow this to happen theirs Ethernet Nics their areToken Ring NICS, they all send data in big blocks, pretend we have a nice big file, what allows asynchronous INT14, synchronous INT52, take data in memory and transfer a whole block of data and get transfer to the NIC, the NIC can receive this, one INT big block, incase of Ethernet how big is the block with either it will take data up to 1500 bytes and move it to the nic the nic has a block of data, up to 1500 bytes the NIC like a the UART, NICS also prepare the data, 1000 or 500 bytes long,

Last questions test 1 what is Ethernet and how does it work?

look at the synchronous aspect of Ethernet, it will put extra stuff in front |SourceAddress| and |DestinationAddress|, before it sends data it puts 8 bytes, the total 64 bit frame, in front of everything, this is called a Preamble, and all the bits are 0101010101010101010, The Preamble sets up the synchronization, how can this help with the timing, it would look like positive and negative pulses, on off pulses, now lets pretend we are NICs, we have to start talking to each other we have to make sure we are talking at the same speed, because we are sending big blocks of data, must talk exactly at the bps speed, this is the purpose of the Preamble, the receiving nic tunes into this and understands, both nics work at the same speed, ordinary nics to 1000billion bps, the nic does not sample at the wrong moment, Ethernet has two tricks, a 1 bit type, ur nic determines if it a 1 bit or a 0 bit, it maintains sync of the digital pulse itself, it syncs and when its reading in the bytes and it maintains sync, because the sampling of the digital signal to maintain a connection, because its doing this protocols can do an enhanced data checking, this is almost 100% error detection, all use this use this system called CRC cyclic redundancy checking, an error checking process, all protocols use this.
In the exam ten protocol questions they all do error checking in the same way

INT52 interrupt cpu, it downloads 1500 in the memory in the nic 1200 bits turn them in memory, its data, but to a nic it’s a big binary number, 1500 bytes long, nic has a micro processor, good to do division, we divide the data by a magic number, the text polynomial, x31+x17….ignore this no one can ever remember just understand the magic number is a standard magic number, the only thing, it 2 standard magic number 32 and 16 bits, soon protocols will have 64 bits, the bigger the more accuracy is built in to the CRC, …so pretend its 32 number and it does long division, what CRC does it ends up with a 32 bit remainder, which is the CRC, they stick this at the end of the data and its ready to be transmitted, when its transmitted same division same magic number and it comes up with the remainder and compares it, and if their identical then the NIC is 99% protected.
Synchronous transmission and Asynchronous transmission….5-6lines paragraph,

Asynchronous -The Past- Week2 DataCommunications

2007-09-15T09:03:00.001-07:00

Every computer was made asynchronous, but all the computers in Canada has been modified to send data with synchronization involved, asynchronous transmission is characterized, its most essential feature it sends data at one byte, one character at a time, each character is a separate transmission event,
How does a compute/transmit?
you can write your own commands, what’s an interrupt, do something and pass control to the Central Processing Unit, there are a lot of interrupts….sending a character to one machine to the next,
01000010A
01000001B
Lets say we want to send the B to Belgium what you do you do, have software, INT14 it does one thing it stops the CPU looks at a specific address in the computer memory it will take the data and send it to a special chip on you mother board, every mother board has one of theses a UART, take your computer apart u will find one of these, Universal Asynchronous Receiver Transmitter, every mother board has one, weather you have one, sadly you don’t use ur UART, it does three incredible things, it moves in parallel bus, but you cant send data 8 bits at the same time, because to send 8 bits at the same time you would need 8 leads in it and you don’t find it, theirs essentially two, one for sending and one for receiving, you got to send data 1 bit at a time, in a serial manner, when you send stuff to ur printer you send it parallel, the UART takes ur data and sends it through the serial port, 1 INT and all it send was 1 Char, a million char it’s a million INT, imagine that you want to send a huge file to your buddy the CPU gets interrupted every time, you cant just send eight bits out of your serial port the UART has to prepare each character, it prepare 8 bits, how does it do that?
Here are our 8 bits B 01000010, its ready to get sent out but first, the UART put some extra info in the a start bit and a stop bit , it will add something called a parity bit, the start bit can be zero or one,
The start bit is always 0’s
Why is that?
Back in the day when ur grand-mama was taking datacom their was a teletype device, some one can type to one typewriter and go to the other one down the line, if no one was sending data, the type writer would send a constant stream of 1 bits, this tradition exist today for the 70% of people using modems, two modems are not sending data but a constant stream of 1 bits, imagine constant stream of 1 bits then it gets a 0, it sees the char coming it reads the whole character and at the end it discovers a stop bit, which is a 1, which faithfully it puts the line in an idle condition waiting for the next character to arrive, UART puts a start bit and end bit, and the parity bit, the parity bit is an error checking mechanism, in the old days, when you were settings up your Operating Software, you set it up odd or even parity, what does this mean ODD parity, odd parity means the number of 1 bits in the character has to be odd, lets look at the B
0100010 we want to send it somewhere the ur is going to put the party bit which would be a 1
101000010
Because the number between the start and stop has to be a number, it’s a even number it will use the parity bit to be odd, imagine a bit error has happened, and a character has changed, it arrives at the destination and it starts to count the 1 bits, and it counts 4 and four is not an odd number, so theirs an error, this is prob the most dangerous idea someone has had, what if the bolt of lighting hit it and it changed two characters and it found the odd the number so its correct, but its NOT correct, still this is efficient enough to work ,

Why do 70% of the world do this? Cause its cheap, cause its virtually free. Telephones network exist to send asynchronous data. The reason it works asynchronous is dealing with 8 bits at a time…

A UART gets a 0 it will sample the first bit then it will sample the remain ding bit, and it will tell if its off, if it had a constant string sooner or later it will tell it cant tell the difference between a zero or a one, it only has to sample the voltage level 8 times, it can still tell a 1 from a 0, then comes the 1 bit and re-idles the start position, every char interrupts the CPU, sends the data, same with receiving, INT14 sends the char to computer memory if you send a million byes you are sending a million int, each int with a start bit and parity, asynchronous is identified sending one character at a time, cheap easy, bad slow and error prone so error prone, Christianson, though parity bit checking is the pits, he will write a computer program that will improve the bits, X-MODEM just a program first of the great Asynchronous protocols, it transmits asynchronous data, with an improvement, its very simple,
How is this!?
Lets say you have a file, foo.txt. and you want to send it to your buddy, all you do is run x-modem, call your body, buddy stats x-modem, as soon as they know they are both running it will see each char and store it in memory in fact x-modem reads in 128 char and stores them in memory then it does parity checking
01000010
01000001
10111100 <-- parity bite, a BLOCK CHECK CHARACTER, then x modem starts sending 128 characters, then it sends an x char locks and checks char, x character running on the other machine will save it and when it receives 129 it will block check carrier, it compares by doings its own block character check, if its both the same and 90% guaranteed, so this has improved error checking, if their different x-char will send a char to the other machine asking for a re-transmission, how does it do it sends a NACK, negative acknowledgement, special 8 bit code means their has been a error, if there is no errors the machine sends an ACK, acknowledgement char, when you log into the cisco routers through the console char, HYPER TERMINAL is crappy or x-modem, x-modem, y-modem, z-modem, file transfer protocols, the original intent was improving error detections, we evolved to file transfer programs. That’s it for asynchronous.  This is Test 1,

Winter 32 divide 4 eight bit octets

2007-09-13T13:59:00.000-07:00

32 divide 4 eight bit octets
Each octet 0-255
Network Id Host Id
Network Id, common and shared by all computer through each physical segment.
192.176.11, Each would have a unique have host id. 201
Each physical segment has a unique network id, another physical physical segment will have another Id, then it would be shared by the computers on the physical segment. Give each physical segment a unique host id.

What is a physical Segment,
Broadcast Domain portion where it is forwarded it, Routers DO not forward broadcasts, All devices one port of router or two routers is a physical segment, all hosts on a physical segment share a physical segment.
Host, unique ip address to for the network, all devices physical segment share the common Network Id, specified by the sub mask. Each Physical segment unique network Id, all computer share the physical segment id
Class A B C [D E]

Class A 0 bit of the first octet, 0000001, ~ 1.0.0.0 , 11111110 ~ 127.0.0.0 < loop back address

33.0.0.0, all computer will be 33, then host id to individual computer
1.0.0.0 ~126.0.0.0
Host ID east remember the last three octets are reserved to host id
Each 256 address
Take Three Octets
256x256x256 ~ 16 million possible address, subtract -2 from it cannot be all 0 or 1

33.0.0.0 all computers start out with it
16 mill dif host Ids First 33.0.0.1 ….increment to 255, 33.0.1.0….increment 255, 33.255.255.254 16.7 mill address

Class B Binary 1.0

Class B 152.77.0.0 255.255.0.0 5000 hosts
Our job to set up addressing

IBM hails nanoprinting breakthrough

2007-09-12T07:30:00.001-07:00

IBM hails nanoprinting breakthrough

OPS435 Week 2 Lecture 3

2007-09-11T13:40:00.000-07:00

Week 2 Lecture 3 OPS435

The handout is the page tells you the 9 steps the shell tells, you interprets
3. ~
4. ‘ ‘ $()
5. $
6. * ? []
7. ‘ ‘ “ “ \
8. < > >>

Once you go through steps 1-8 the shell has interpreted the command and executes it 80% kernel, 20% shell, if its built in then its already in the shell, if its not a built in command the shell has to pass it on to the kernel before the kernel executes the command it has to copy it from the database to memory, the kernel does not know where it is in the database, that’s another function of the shell, it must tell the kernel where to it is in the database, How does it know….path variable

Lets say where doing the ls command, it must go into the $PATH variable and its going to go to the first variable and sees if its their and goes to the next and when it find it it passes the information to the kernel, then the kernel will go and copy the command or utility from the database to the shell and assign it a unique PID number, it will go back into memory and release the command then the kernel goes and nudges and shell and says its done and asks what do you want me to do next, to finish this one off we have a command
Mail –s “$host System Maintenance Warning!” ‘cat ~/userlist*’ < maint01

There are two commands, command substitution ‘ ‘, the car command will be executed before the mail command is executed

As soon as the command their it executes Token Splitting, then it looks inside the ‘ ‘ and find the tild which is 3, it will take the tild character and replace it with the home directory, then it goes to number 6 because of the star it is looking at the ‘cat ~/userlist*’ it will go into the home directory and look at any file starting with the name user list, userlist* will be replaced will all the files with the names matched, the cat command read the contents of the files, so the whole cat command will be replaced with the STDOUT of that command and will be replaced from ‘cat ~/userlist*’ this and will send the content of the directory of all the user names, so when this is done the shell will continue to 5 and down, so were looking at the $host and will replace the $host with matrix, 6 no, 7 quotes yes the quotes are their, the quotes will be removed, 8 I/O Redirection yes < STDIN which will open the file read the contents and pass the contents to the command, during step 8 it will open the FILE, all the interpretation is done when all of its done, in step 9, after step 9 it will pass it to the kernel, it will go to the path variable to find where the mail command is located, once its done the shell jobs is done and the kernel will take over from their.

> clears the file and prepares it for receiving data,

1,4(1,3,6,9) 5,7,8,9

Another example when the shell does not go through the path variable, 1 when the command is built in 2 the mail command, instead of the mail command you put in /bin/mail…will the shell go to the path variable…no because we have already specified where the path is so the shell does not have to find it because this is absolute addressing. The shell is about different characters, that is how you ask the shell to do things, if you don’t know the special characters you do not speak the shell’s language.

Covering a couple of commands you are going to need a number of commands for Lab 1, Lets start off with the sort command, sort command not a easy command, and is very complex if you make use of all the capabilities, lets go through the command, there are two different sort command the old and the new,
Sort sorts the contents of the file and puts them in an order, what order, it uses ASCII code for its default code for sorting everything you may use many option to change what it is to do, but remember its done automatically by ASCII code, both new and old work that way.
Capital A 101 comes before small a 141, Numbers come before Capitals

With the sort command you can specify, lets do this
sort f1
if you simply do this command will start sorting from what character, the first character, most files are split in fields, you can specify which field you want, it automatically goes to field one though,

The difference between old and new how you specify how u want to do this
The old is SKIP SORT the programmers that divised there is no other reason, the reason its called this, say you want to start on field number 2 instead of says start on field 2, the skip sort asks what field do you want to skip to start on so
Sort +1 f1
+ means skip 1 and this command will start on field 2

With the sort command you say start on this one and stop on this one, multiple fields of starting and stopping lets say you wanna start on field two and stop at four

Sort +1 -4 f1

Lets say you want to continue
Sort +1 -4 +5 -9
On 5 and stop at 9, what field are we going to do its ASCII
6 through 9 are numbers, if you wanan sort numerically you have to tell the command you have to use –n so if +5 -9 is only numeric you put the n here
Sort +1 -4d +5 -9n

The d is for dictionary field, that is basically how it works, now you can also specify….not important….how to start on a certain character field #5 and char #6 you can be very precise, you can look that up in your man pages if you wish. Particular char then a field, so that the skip sort command the new skip command is called key word sort the only difference is how to specify the fields you want to stop and start on, it keys exactly to the field you want to go to

Sort –k
As soon as k keyword sort command, so we want to do 2 4 so.,,
Sort –k2,4d –k6,9n

It is the same as
Sort +1 -4d +5 –9n

We are going to look at some other options on this command, the default delimiter is white space, tab and new line this is called white space,
Now what is the delimiter in the file /etc/passwd its semicolon, what if you want to sort in a file with semicolon so you have to have the option to change the delimiter
Sort –t: that will specify what type of delimiter it is.

Sort /etc/passwd

Sort –t: -k3n /etc/passwd
Or
Sort –t: +2n /etc/passwd

-f force case insensitive, don’t differentiate between upper case and lower case you use –f

-r sort in reverse

Lets try another command cut, what is the purpose, you can cut data from a file, you may cut portions for any particular purpose, so the cut command you specify what is it you want to cut

Cut f1

The type of data it was designed to used the default delimiter was a tab, it is not white space but a tab, so any time you use it you should know the default delimiter was a tab, if its not a tab you are going to have to change the delimiter what is the delimiter change for the cut command

Cut –d: f1

You cut either fields or characters with this command and the way you do this, there is another option in their which is cutting fields

Cut –d: -f3 f1

Three through 5
Cut –d: -f3-5 f1
Three through 5 & 7
Cut –d: -f3-5,7 f1
Range and the command says and this

Also –c characters you can cut characters so you can say
Cut –c10-20,25,28

And that’s the cut command, another command

Paste

One easy way to remember how it works, everyone knows how cat works
Cat 1 2
Its going to append the two together vertically, the paste command works similar, instead of vertically it appends them horizontally, its going to put a delimiter which is a tab between the two

Paste –d+ banana

Instead of the tab it will have plus signs.

Paste –s
Which means squeeze its going to take the whole file and squeeze all the files into one single line. Single file only.

Remember all the commands you are using it does not do anything to the file, the original data remains as it was.

Here we are going to try something, assign a variable age you year of birth in this format
YYYMMDD
$age = 19871223
Echo $age |cut –c1-4
1987
Echo “The year of my birth is $(echo $age | cut –c1-4)”
The year of my birth is 1987
Echo “The month of my birth is $(echo $age |cut –c5-6)”
The year of my birth is 12

The shell basics with commands, okay Chapter 3.
Login Files, when you log onto the system there are a couple of files that are automatically excuted when you log in the shell environment is predetermined by these three files
/etc/profile – this sets the environment for every user, same file to every user, which belongs to root, and super user can use this to set up the file for every user
Two other files
~/.bash_profile – the user is in charge of this, if you want to change your environment you would go into this file, if you want ur prompt to look different you can go into this file, if you want to create a new command you can put alias command and when you log in it will stay their.
~/.bashrc – this belongs to the user as well, and you can go to either one and make changes to you environment.

~/.bash_logout - when you log out , want something done when you log out u do this

Open up ~/.bash_profile
cat ~/.bash_profile
# .bash_profile

# Get the aliases and functions
if [ -f ~/.bashrc ]; then
. ~/.bashrc
fi

# User specific environment and startup programs

PATH=$PATH:$HOME/bin
BASH_ENV=$HOME/.bashrc
USERNAME=""

export USERNAME BASH_ENV PATH

PS1="\[\033[21;255;44m\u@\033[21;255;44m\h:\033[1;255;41m\w$\033[0m\] "
LS_OPTIONS='-N --color=tty -T 0'

Cd what does this command do, takes you to your come directory

Cd - - takes you back to where you were before
Pwd
Random – echo $RANDOM you get a random number, if using a program and you want to generate random numbers that is how your going to do it

Shell Built Commands are on the slides….

Special operators …first semi colon what does that mean to the shell?

Cd
echo
Cat
Sort

Writing a program so on every line lets say we want to do all the commands all the same way but we want it on one line
Cd ; echo; cat ; sort

; - command separator
& - used for

Sleep 10 – shell sleep for 10 seconds
Sleep 10 &
[5] 15962
Job #5 and is running in the background and gives you the environment to play with still, it will assign the job number and run in the background, if you hit the return it wills say job #1 is done.

The labs are normally due the date, but we going to do if u don’t finish on Friday up to next Friday.

DAT702 Week 2 Lecture Three

2007-09-11T13:36:00.001-07:00

Week 2 Lecture Three

The lines connecting each table are relationships between each other, the connection allows you to put data in the corresponding field if data is in the first field, the constraint belongs to the foreign key table, one of the most important tools networking people will do is moving data. How many people have a Royal Bank account in Canada, about 6 million, you will be bringing data in bulk, we are going to be doing it in Access as well as MySQL, Access does not like a lot of tables opened up, which table are we going to use first, courses and students, grades must be last because of the constraints, the students file is tab delimited and is correct the very first line is the headings of the table, in MySQL you cannot have headings in the file,

Now we are going to open:
File/Import/students.txt

Defaults to Delimited, Tab, Click first row contains the field names, Text Qualifier =Always None, next then loaded

Two constraints which are the students and courses to the foreign key which is the grades table, data must be imported to the constraints then when the constraints are loaded you are able to load data into the grades table. Remember the Constraints to the foreign key. Appropriately

In Access go to Query/ Right Click screen SQLView type

SELECT *
FROM students;

OPS335 Week 2 Second Lecture

2007-09-11T13:29:00.000-07:00

OPS335
Second Lecture

Today we are going to be talking about Disks, 1956 IBM made the first disk which was 5mb, about 50 years ago, and cost about $50, 000, contrast this from 2007 called the Desk Star 1000, 1TB - $500, there is new way to give 50% more capacity, as technology progresses everything gets cheaper. Disks, we use them for Non- Volatile Storage, information is saved when your computer is turned off, that is one of the systems storage, your memory is Volatile, what ever is in RAM is gone, but in you hard drive the data will still be their, we use this type of storage to store programs, video clips, photographs. Now you can purchase, NAS, Network Attached Storage, you can buy them now at Tiger Direct or Future Shop, it plugs into your Ethernet. You can store stuff on it, drives may go away in the future because of chip memory, hard drives are mechanical with moving parts the disk is rotating, chip memory will probably be faster in the future, you may buy memory cards for you camera this is an example of chips out doing Disks. A picture of a disk…we can write on the top and read at the bottom we have 8 surfaces we can do our reading and writing, in the example of the cylinders the tracks are concentric tracks its circles into circles, if you take a look at one particular track and ask yourself how much data the track can hold and multiply the track by 8, it will give you the capacity of the cylinder, the cylinder is the sum of the tracks in one sweep through the surfaces of the platters, so you have a sector here which is the smallest part of the track, a sector is typically 512 bytes, if you have a file it will be written into a whole sector the system cannot read more then a sector at a time, they cannot read one byte but a sector at a time, these are all of the attributes of a hard drive,

Looking at the zones of the drives, the top platter, you have 5 different zones, every zone the number of sectors, you can count the sectors and in our example its 9 sectors, as you get closer to the centre its harder to squeeze in data, as it branches out form the centre you can have more tracks, in the early days a disk only had one zone,

C=T*H*S*Z
The formula Computing Disk Capacity
C is the capacity size of the drive measured in bytes
T is the number of tracks on one recordable surface
S is the number of sectors per track
H is the number read/write heads (usually the same surfaces)
Z is the size of one sector usually 512 bytes

For pcs a sector is 512 bytes, lets take an example we have a disk with one platter, if it has one platter it has two surfaces, so it has 2 sets of r/w heads, we have 18 sectors /tracks and 80 tracks and 512 bytes per sector
H=1 platter * 2
S=18 sectors/track
T =80 tracks bytes /sectord
Z = 512 bytes/sector

Echo 2 *80*18*512
1474560 bytes
Divide by 1024 we get 1440Kb = 1.44mb this is like a floppy this formula works for every single hard drive unless you have a hard drive with multiple zones, then you have to work out the capacity for each zone, if you have six zones on the hard drive you have to do the complication 6 times and write it down, 1024 bytes is one kilobyte, kilo, mega, gig, tera peta, exa, zeda, remember we only 10^88 electrons in the universe, those are the standards, take a look at the example he did, he wants to know what is the capacity of one cylinder,
The capacity of one cylinder,
1440kb =1.44mb
Capacity= 2*18*80*512
=1474569bytes
=1024

1474569/80x2 -this is one cylinder
36864 bytes

Cylinder, we have two plates, if you have 2 plates you have four surfaces, the track 0, 1 platter is two surfaces, the cylinder will be the first track and the track under it.

Cylinder Y= H*S*Z
=2*18*512
=18432 bytes 1 cylinder
Size of one Track divide by 2
T=9216 bytes

Why is it important to know what a cylinder, because when we partition a hard drive we have to partition a hard drive, every partition you make has to be an even number of cylinder, so the smallest partition you can make is one cylinder, Linux on the other hand cylinder/track/sectors/heads does not really care that much,
fdisk –l shows the partition table,
dd if=/dev/sda of=mymbr bs=512 count=1
copy from to
file – what kind of file is your mbr
with fdisk with p it will show you the partition, if you want to delete d of partition number 2 and p will print and you will not longer have a partition 2.

Capacity = 64* 32*17547*512
18399936
C= 128*16*17547*512

E-mails are sent a week before
What is in /boot:
/boot – kernel ram disk file, grub file.

Second Lecture OPS435

2007-09-07T16:02:00.001-07:00

First Week Second Lecture
OPS435C
Frank C Russo

Directory Structures, in Linux its not much different from many other systems if you want to understand this its easy to remember because its similar to your family structure, parents, grand parents, to your children and grand children

Databases contain information which is located in different directories this is where the directory structure comes from, this starts from root,

Typed cat dir.sir…showed a detailed directory

An example of linux directory structure it starts at the very top with root and under root you can subdirectory and files, and each of these can have their own subdirectories and files, when you address a file or subdirectory you have to tell the system where the data is located, there are two different ways, one is called relative and the other is absolute, absolute addressing from root always, relative starts from where you are Current Working Directory, if you need to use a command you can mix the two, part in realitive part in absolute, there are many instances you must have it in one or the other, if you addressing the /etc/passwd, you can do in relative but it takes to much time be efficient, and since you know where it is you can use absolute addressing to get to this file, any thing that the program creates should be in relative, because if you create a program you don’t know the other persons directory structure this makes all the data go in the right place correctly. You must know when to use what. In our assignments it will become clear, lets make sure how each one works, this is a review we must understand how to access databases,

For instance you want to change the directory from where ever you are to go to your home directory what command do you use? Cd command with no arguments takes you back to directory, if you add a ~ (tild) it takes you home or $HOME it’s the same thing, the shortest command to use is cd, with three simple commands you can navigate to structure,

How would you know what dir you in pwd, the files to list ls

Lets assume your current directory is steve how would you change your directory to steves parent which is usr, type cd .., cd ../.. (grand parent directory) in our case would be root,
Think current address is steve
Relative ..
Absolute /usr

What is the A and R address for math
Relative from usr program/math
Absolute /usr/steve/programs/math
The shell automatically starts from the current directory

Subdirectory data from steve, up one then across
Relative ../john/data
Absolute /usr/john/data

Remember that the command line is case sensitive, with 99% we are going to use we are going to use data from the database, so you have to address data from the database, KNOW REALITIVE AND ABSOLUTE, quiz one will have a lot of both….make sure to review.

Linux system directories, in the Linux strcture there are number of directories these are what they are and what their used for
/bin = holds binary executables
/boot – holds the Linux Kernel
/etc – contais configuration files
/home – the default home directory for users ($HOME)
/lib – contains library files
/mnt – contains mounted drives (can mount structures to other ones or as a part of your own)
/root – the root user’s home directory
/tmp – contains temporary files
/var – contains files that change

/  all encompassing root directory
/root belongs to the user root

These are all in each Linux system

Examples :
Cd brings us to your home with a ~ tild is the exact same thing
~john - brings you to johns home
~/john - brings you to ur home directory to a subdirectory john

The Shell automatically replaces the tild when it does the interpretation of the command to what ever the home directory is, it will replace the variable name with the content which is your own home directory

When you execute any commands the requirements of a command most will require an input of some sort, by the user or system itself, if you do an who, the input to this command is provided by the system itself, it provides an output, theirs an STNINP then STNOUT ….where does STNOUT go it goes to the screen by default STNOUT goes to the screen, unless you direct it somewhere else, STNINP where does it come from…the keyboard
Type

Cat file
Where does STDIN come from…it comes from the file, you have told the command to get the STDINP from the file and STDOUT put comes from the screen,
Cat …with no arguments
It waits for input (keyboard by default), it comes from input Ctrl-D takes you to the next line.

STDIN STDOUT & STDERR

Where does STDERR go to by default…on the screen, so you can see it.

Those are the three things we need to understand.

Special Characters the shell interrupt all special characters

< - Redirect STDIN this is also known a file descriptor, there are three file descriptor

0< STDIN whether you put the zero or not it knows

1> 0 Redirect STDOUT

2> STDERR

Knowing this what would happened if you redirect a file a into c, if you follow the cat command will read the contents of a then go to b then it will produce a STDERR then the STDOUT it will go into the file c you will not see the STDERR and if you execute it you only see the STDERR

Cat a b > c
Error!

Cat a b 2> c

You will see the contents of file a and the error b will go into c and you will find the error in c

What happens if we want to send both,
Cat a b > c 2>&1

Theirs two different way to redirect both STDOUT and STDERR this formation works in every system in every shell, this is standard, 2> redirect STDERR &1 to the same place to STDOUT was redirected, nothing appears on the screen, and if you cat the c file you see both.

Rmdir –r – remove that directory recursively all of them

Permissions, ls –l

Read
Write
Execute

Ls –l
O G N
- RWX RWX RWX

- - File
D – directory

Owner Group Name

Ls –l tells you what group you are in….
For a file you can read, the contents of a directory you can see directories, a directory does not contain files or subdirectory, it contains the names of the files of the subdirectories, when you reading the contents of a directory you are reading the names of the file and subdirectory, so if you have read permission, you can use LS for a directory for a file it would be CAT,
To write into a file you need write permission, when do you need to write into a directory, if you create a new file, you are adding a name to the directory, you are modifying the contents of the file, if you delete a file you are taking the name out for those you need write permission for the directory,
X execute it allows you to execute a file, better be a program or a script, how about a directory can you execute a directory, the X has a different meaning to a directory then from a file, what is this meaning for the X for a directory you are allowed to get into the directory the X is a the key to get into the room, think a closed door, if you do not have a key to open the door you cannot read the file.

X – pass through permission, allows you to go through it

Cat / home /joe /dir /f1
X x x x r -minimum permission for the command to be successful
.
Cp / home /joe /a ., /b
X x x r x w - u need to read to source and write to destination
If it doesn’t exist (b) you need to write permission in the home directory

Cp / home /joe /a? .. /b
X x xr r x w

The moment you put a ? is will read the contents of more then one file so the directory joe must have read permissions in order to read and match the files.

Tips: Look at every directory ONE at a time, any time you are using file name expansions character ? * [] you are asking the shell to match, so the shell has to have read permission to read the contents of directory.

We are going to be using vi so go through vi stuff.

Copy command you must have a minimum of two arguments
Cp a b c d
Copying it into a directory, more then one file you have to copy it into a directory

-I - Interactive, it asks you for each file

The move command mv, same as the copy command

Handout

When the shell interprets it interprets every line and goes through 9 steps each and every time, these are the nine steps the shell goes through….

Know the 9 steps
1. Token Spitting: When the shell looks at the command line breaks it up to each individual word and looks at each one, one at a time…happens with every command line
2. Alias Substitution: Known by many different name, in Linux you can create new commands in Linux you can have a regular command even Ls and give it another alias, when the shell looks at the command it checks to see if it’s a real command or a alias command…greater detail in later Lectures.
3. Tilde Subsitution – Looks for the tild its going to replace it with your home directory
4. Command Subsitution – Greater detail later, you can have one command inside another and into another one, like the algebra you look from the inside out, same thing happends with this process the shell takes a look at the special characters and tells it command substitution,

When we introduce special char jot them down, when you have a command inside backquotes this is command substitution, the shell must execute it first, replace the command with STDOUT of the command, another one is dallor parenthesis is the same thing
‘ banana’
$(banana)
5. Parameter Expansion: The special character for shell variable expansion how does the shell know it’s a variable name and not text…with the dollar sign $var when it replaces the variable name with the contents its done in #5
6. Wildcard Expansion: What character is it looking for examples * ? [] those are the three characters its looking for in this step, when it encounters them it will go to the directory and replace them with the files that it has matched
7. Quote Processing: What characters are quoting characters their single double and the other is a backslash

‘’ (single quote) – in Linux anything inside this does not have any special meaning, no special characters what you see is what you get.
“” (double quote) – same as single quotes with three exception, there are three characters that retain their special meaning in double quote which are $ ‘ \ dollar sign, single quote, and backslash

Try something
a = 1 2 3

To read this echo $a and it will echo the contents 123
Echo “$a” view 123
Echo ‘$a’ view $a

The meaning \ its called a single character quote. Backslash the character following me is not a special character,
Echo \$a view $a - the shell will not interrupt $ as a special character because of the \ (backslash)

\\$a view \123 …. \ makes it so \ is not special following everything executes itself

8. I/O Redirections : STDOUT STDIN STERR, it will do the redirection when found, but when the shell….do this
Sort f1 > f1 - when you do this command before the command is execute the moment it encounters its going to clear the contents of the file then you are sorting Nothing and you redirect nothing into f1. This step is done BEFORE its execute

9. Execution: Command is execute : most of the time the kernel execute the command the only time it doesn’t if those commands are part of the shell a number of commands are apart of the shell, when the shell is in the memory what ever is in the memory you don’t need it to bring into memory then to shell, those get execute in the shell, theirs a list of the command they are 20% of the commands 70% is executed into the kernel.

How does the Kernel know where to find the command, the shell goes to path variable searches through all the directories and searches where the utility is located, execute this command and this is where to find it, the kernel copies the command to the database to the memory goes to the memory then goes back to memory then it goes back to shell and then asks the user what they want to do again.

Second Lecture DCN386

2007-09-07T15:58:00.000-07:00

Week 1 Second Lecture
DCN386

Next Question,

What is analog transmission and how does it work? (5 mark essay question)

In the history of communications, two important technologies their was analog at the beginning then their was digital, for week 6 you have to figure out why digital is good and analog is not, in fact analog transmission in Canada is non-existent, its making a come back through fibre-optic technologies, it uses analog.

What does the word analog mean?
Analogous it means that something is the same as, but not identical, visualize is two objects such as two different color markers red and blue, they are analogous, we are going to reinvent the telephone go back 120 years and reinvent the telephone, when people use analog transmission that means they are sending information through a phone company service,
What do you need to invent a telephone?
We need a power source, we need a circuit, we have a power source and a complete circuit of electricity will flow down the circuit,

Drawing of a circular wire with flowing electricity, its 60 ohms per-second, now were going to send the power through the circuit, but we want to modify the wave and change it in such a way to reflect the sounds you make when you talk into the phone, you voice which is a wave of sound is being transmitted through the receiver, how do we do this it is very simple, we are going to have a tiny container, in the container we are going to put a magical compound, a semi-conducting compound Carbon, which is a semi-conducting compound, in between the carbon we are going to put a membrane of some sort, carbon has a magical trick when it is compress it conducts electricity better, membrane is a wire and the sound will be analogous to the sounds that you make, we now have invented a telephone, the theory is as simple as that, at the other end of the circuit, there is a speaker as this goes round it vibrates the cord and you can listen to the sound on the other end.

What does this have to do with datacom….nothing at all, but for the longest period of time in Canada, all computers needed to make sound….modems made the sound for the computer, modems would take data, and change a beautiful even pattern to represent a 1 or 0 bit, that is all modems do, now we are going to invent modems,

If he gave us ten bucks and went to a garage sale u can buy enough equipment to make one,
Modem processes two different sounds 1’s and 0’s the receiving modem knows the differences in the sounds and will re-create 1’s and 0’s and process the information.

Ever see a old fashion volt metre? It is basically a little box connect to a circuit to both sides it swings it will be negative or positive, find one of the devices take it apart and put the arrow thing into a shoe box, you attach the voltmeter to the serial port to your personal computer, the same that you stuck your port into, to talk to another computer…..how does the computer send it out to the box….analog or digital?….digital of course, even when data is being send over the serial port, drawn 0100001, carry an ASCII chart with you, show your ASCII chart to everyone!, that binary was an A key theirs a special interrupt called INT14 and it will send the process through the cable in a series of pulses, in pulses some are positive and some are negative, back to our arrow, are little arrow goes up and down when transmitting data, we invented a modem with a wire attached to a bell at the other side, when the pulses go through the wire it will hit the bell on the other side and it will make thebell Ding Dong representing 1 0 1 0 1 0, all you have to do is invent a device on the other end to read the 10101’s and re-creates to make the sounds, modems create sounds, the sounds are interrupted by other modems…digital data that is re-created….modems……remember the noise when you got the number wrong, and the operator was in ur modem….i tripped out to that lol YO THEIRS A VOICE IN MY MODEM….picked up the phone…couldn’t connect to battle.net

The first modem was the Bell 102 , Miracle new technology, first modem beautiful thing it ran at 300bps, how many characters could it send in a minute? Before we talk about how this works we are going to talk about

Analog telephones, for years telephone engineers studied people normal conversational sounds, they realized human beings can make very low sounds, some people have high voice, but for ordinary conversation it was discovered if you have a frequency range…what does that mean….low and high waves, the lower the frequency the further you can send the signal, the higher the shorter the distance you can send it without being amplified.

200hz and 3400hz is a standard range sound can travel at a distance, your LAN phone filters out everything 4000hz, hertz, Who was the inventor Dead German Guy, created the cycles per second which are hertz.
How can you prove that the lower the frequency the further the higher the shorter?
He drew a wave with a whale under it, can a whale can swim 100 kilo at 100 hrs because it has very low frequency, if you have a sparrow if you immerse him into the sea water the sparrow will not be able to swim because it has a high frequency sound, when you talk all sound you see it in that range…

Modems learned how to make sound between this range, and they operated in the telephone network, modems work by a simple process, first when they talk to other modems they both send down a carrier wave, this is a very fixed amplitude ,fixed frequency, it will be modified to represent 1’s and 0’s how many ways can you modify a wave, how many can you do this,

How many ways can you change it?
You can change its amplitude, you can increase or decrease the voltage which is basically called its amplitude, another way you can change it is some instance in time radically changes the frequency this is called frequency change,

If it wanted to change the amplitude it would have to have different amplitude levels, theirs an increase of voltage to send bits, all modems have used frequency and amplitude , modern modems use phase change,

We have to understand amplitude, frequency and phase changing,

We went back to the 200hz 3400hz restrictions sound can travel on a telephone line we sent down 300hz, because it went down 300hz it achieved 300bps, modems like computers, their has been pressure on the line, just on computer manufacture and producing its products, the pressure has been to make modems faster, that has been the challenge for the 45-50 years, given the primitive technology how could you double the speed,
Why is it called a bell modem, when he was a kid and datacom was being invented no one made modem except bell, when you order a analog for data, a bell modem came, so how do we get from 300 to 600 bits for second, simple you send the a carrier wave 600hz, u have 600hz, and 1200hz, the oldest modem went to 56000bps how is this possible that has a maximum carrier wave of 3400hz max,

How is this possible?
With our primitive concept of only two different changes, someone wanted to develop a 24000bps came up with a place to send 2 bits every time the carrier wave was changed, 24000bps modem (drawn) inside the modem their was a buffer, a memory stick very small, the modems receiving is not sending them immediately, 01000010 (represents b). In the modems memory the modem it is going to analyze the character and break it into two bit pieces, now two bits can only be arranged four different ways, which means our new technology modem is going to need four different ways, its going to analyze the frequency it knows what the carrier frequency is, it is going have the ability to send it depending the two bits see how easy it is we are going to keep to 1200 hertz, every time we change it we are going to send two bits which is 24000bits per-second, now we need a 48000bps modem, this actually happen someone increased the frequency to 16000hz and send 3 bits, if you have 3 bits how many frequencies would you need, f8 we would need eight different frequency, carrier wave 16000 hertz every time we send it represents 3 bits, we got ourselves up to 48000 bits per-second, now we need a 9600 bits per-second we are going to send 3bits increase the frequency 48000 hertz send 4 bits , if you have four bits how many different ways can you send the data, this is where technology hit to the wall, 16 frequencies traveling down the line became very difficult, not understandable through the transmission, their was a new way, modern70% of the poor people in the world are using modem, and that technology has a limit, quadrature amplitude multitude, QAM for short, it applied a very unique method for modifying carrier method, uses two completely different attempts simultaneously they do phase changing, (know -amplitude frequency and phase changing,,) a normal wave through a line and what if the information went half round stopped and went around again, it would be very unique or it could do a change at 180 you can tell the difference, or it can do a change 280, or now not change at all, we have four different phase changes so we simply make up a rule, look at the 8 bits of the modem and analyze each 4 bits, for the first four bits from the right we are going to do a phase change for 90 degrees and we are going to do a phase change to 90 degrees to increase, and we are going to 90 degrees and leave the amplitude alone, we are going to do a phase change 180 we have four different phase changes with two different amplitudes, giving him, we have the ability 4 bits using QAM, this gives us max of 96000’s bps, QAM is used by the way using to fibre-optics,

What was the best modem ever invented?

56kb was not a true modem….Explain Why?

The last great true modem was the V34 modem a pure modem it was the modem that pushed to the limit of the carrier wave, the CW was 3400 hertz, but it could send every time it changed a CW, how many bits does it need to change the carrier wave, 256 different way’s to change the carrier wave, go into and type V34 specification the last true modem, how intelligent was it, it was very intelligent, once connect 3400 maximum, if the smart little V34 modem was getting a lot of errors it would send the a signal to the other modem and cut down the CW 2400, 1600, 1000…..Errors, 50% datacom studies 50% of the deal is the detection and handling of data errors, 50% is involved how does it detect errors….

The Bank Machine, what if you asked for $100 and their was a few bit errors, computers can not tolerate 1 bit, this is a catastrophe, just one bit.

BREAK

What’s Question 3,
What is digital technology and how does it work? Essay!

What does it mean to digitize something?

When you digitize you are turning something into a number.

The technology we are going to talk about its going to be a binary number, all it is, is turning information into numbers, before 1980, phone companies around the world started replacing analog technology with digital technology, 1980 Bell Canada Banner 100% Digital, in their backbone network its 100% percent digital, the phone from your hose to the bell office is analog, we are be talking about digital for the rest of the course for the next 13 weeks
A simple question…
When you talk on your telephone and it does to the Bell office it turns ur voice into numbers

How does it do this, some device turns ur voice into number, from your house theirs a telephone cable that goes under ground to the closest Bell telephone office connected to a computer a special process computer, it directs your phone call, and turn you voice into boring binary numbers how are you going ti invent digital technology, at the end of the line, think voltmeter it is going to listen to the sounds and the volt meter will pass info to a microchip, its only about $15 bucks, technology is deceptively simple, here what the phone companies did before 1980, they started looking at this at the 1940’s and not complete until the 80’s,
Story of Shannon, knew mathematics, turned his mind on this question, if you want to send digital representation on human voice how many bits per second will it take to represent a human voice, Shannon law was very simple , drawing of a sound wave, long wave, the volts meter will take sample readings, 0.1 Volt 0.2 Volt, 5 Volts, all are sample and each time its getting a number their number Decimal Numbers, the volt metre passes the values to micro chip and it is converted to an 8bit binary number, it becomes a next sample 2.0 volts. How can u represent minuet, the first bit of an 8 bit sample represents –negative or +plus value, these numbers get transmitted through a series of pulses through copper wire, the trick Shannon realized, how many sample per second should you take, so that the voice at the other end sound legible, the Sample Rate, what was it that he came up with, remember the sample wave 4000hertz, the sample rate should be twice the maximum rate 8000 samples per second each sample results in an 8 bit value which means data is travelling down the line, each sample is 8 bits, their for when talking you are talking to someone it is 64000bps, precision is vital in digital technology, this is how it works the tricky part, we are not going to far about today, digital technology is not simple as pulses there is many ways but we will look at 6 ways from this course,

stressing telephone companies around the world, in the middle (Company to you is seen as digital to analog….analog to digital is seen as you to the phone company)

The physical circuit between phone companies T1 circuit…..what does that mean what is a T1….it is a standard in North America called Multiplexing …means putting numerous signals up on 1 wire, very simple, next week, in Canada each T1 circuit can handle 24 simultaneous voice conversation, 24x64,000bps (digital signals)

The really important issue, by week 6 he wants a nice statement to this questions….

Why digital is good and why is analog is not?
Why did the world go digital?
Why do signal diminish?….all electronic signals diminish all signals, because this happens in fibre-optics all signals suffer from the same fact of nature they must come to an end, this is attenuation, which is unavailable, only way to combat this is to send you wire to 0 degrees Calvin, attenuation happens, now ask yourself how can you talk to your girlfriend in Vancouver every 15 cables bell has installed is Amplified, taking a diminishing signal and creates new signals, the trouble with this technique, but we want computer to send data to Vancouver which is a different problem, attenuation is avoidable, but there are several things we call them Noise, the worse culprit is fluorescent light, we place one of these lights to phone line they give of electro magnetic field and when placed near a phone line you get crackles on the line, now when someone is on the phone and you hear crackles a computer cant tell if its happening, here is the worse part amplifiers don’t know the difference either so an amplify the signal will amplify the crack and fluorescent is one way, solar flares introducing the crackles, bit errors worse thing in the universe next to windows,

Digital signals are getting attenuation which happens to digital signal, we are going to run a digital line through the fluorescent line and get crackles, but here is the answer
Why digital good?
When digital technology is introduced, phone companies did not install plain simple amplifiers, they used Repeaters, a repeaters is very different then a amplifiers it looks at the pulse can see if its decayed and makes a brand new decayed pulse Positive or Negative and if it doesn’t know what it is it will filter it out, efficient, making you signal clean and free!

Why 56kbps Not a true modem?
If your ISP still have analog transmission between the isp and the closest bell office the 56kb will not go over something……if your isp puts in a digital service such as a t1 circuit between the isp and the bell office and you install a V90 modem 56000bps at ur house and you put it on a analog line, ur isp is a digital service, analog to digital the technology for doing this is inpercise, analog digital conversion introduces problems, not a perfect technology yet, when you turn on ur V90 modem it realizes its on an analog circuit the modem degrades it self and become a V34 36000bps, when you turn on the other modem and it sees its on a digital it will continue to run at maximum 56000bps it will send 56000bps and you modem at you end will go 28000s, now if you wanted it both ways you have to phone bell telephone and disconnect the circuit and reconnect a digital home service, which will mean it will have to install a new cable and you willge ta service to ISDN, its over priced and will solve your modem problem.

How do you get ready for week 6 you go on google words like
Analog Transmission – Compliment QAM how
Digital Transmission

Digital Good Analog Bad

Telecommunications: The idea of sending information through the air in the form of flashes of light is being given a high-tech makeover

2007-09-07T06:01:00.002-07:00

The Economist.com.....

First Lecture DCN386

2007-09-06T14:04:00.001-07:00

DCN386 First Lecture

Test on week 6 another test on week 10, a lot of lab marks in the cisco room, configure and take out of a router, data communication is career, mainframe computers start from big to small personal computer, the story of a purchasing through cash register, if you buy something a message is sent to the main computer of the company so it says that you have purchased the item. Banks to mainframe computers to lottery ticket machines all these are examples of DTE DATA TERMINAL EQUIPMENT, Sending data is through the NIC card, another way for this is a MODEM 70% of the world use modems, multiplexors MUX for short, there is a collective term for these devices they are called DCE Data Communication Equipment, these are sepretate devices made by different people, How do they connect together they use Standards, last semester for the cables and wireless we called them the communication medium, an example of this would be copper wire, fiber optics, wireless
Can you send data through a vacuume?

Rules for any DTE to DCE we call the rules interfaces, theirs are hundreds of interfaces and we will only learn a couple, again this is standardized, think in terms of data communication protocols, we are going to learnining detailed understanding of the protocols what they do and how does it work?

What is token ring?

It is a older technology, Developed by IBM first but not only LAN technology, complex hard to install, its obsolete now, Zerox brilliant that invented a ton of stuff like mice, windows, taken by Microsoft and apple, the most important thing they created was an Ethernet Network Interface Card, companies have Ethernet, they couldn’t intercommunicate with each other because u couldn’t intercommunicate until standards took over, the group that standardized Local Area Network identify four standards orgnization and tell me them, the first standard organization is the IEEE, started a project in 1980 the 802 family of standards and have been working for LAN ever since, first thing they did was create a standard protocol 802.2, they modified slightly Ethernet 802.3 and token 802.5, wireless 802.11.

IEEE student member,

Another standard group ITU this is a telecommunications union, get countries network to internet with each other, they have standards for everything, TIA-586A or B created provide contractors with a standard way to build networks, we will be talking about later in this course. IETF never invented a standard but a lot of protocols were made by this ogroup, this job is to listen to comments, you may write memos, HYPER TEXT a way of linking sites, www….changed the world, he set his idea on paper and it was tested by IETF and changed the world. Go to the website and look for the request for comments RFC.

First Lecture OPS435

2007-09-06T13:50:00.000-07:00

OPS435 First Lecture

Linux and Unix

We will be able to write scripts and programs in any Linux Shell, to understand how shell scripts and how they work we will be looking at the basics of the shell, oc and grep to search in databases.

The
Kron shell reference - isbn 0-916151-72-7
VI Reference Card, SSC Inc., ISBN: 1-57831-0 05-9
and the bash shell are very similar if you know one you know the other.

We are expected to go through the slides know and understand what it is about because it will be on the quizzes and the test.

A little bit a of Review of what we know about Linux and Unix,
What happens when you start the computer, everything is does it is told, basically you do, minute instructions on what to do before the computer could do anything, when you turn it on the volatile memory contains nothing,

How does the computer know what to do when you turn it on?

It’s a combination of hardware and software, when you turn it on it has to check the everything within the system. The BIOS the program that loads everything into the computer, BIOS is a program it’s a chip which contains the program which is always their, when you turn it on it starts telling the hardware things to do, when it finishes doing that the BIOS passes control to another program, the very first sector of the very first cylinder of the first drive the Master Boot Record, it has 3 sections the first 2bytes are the signature, other wise when the system looks at the MBR it looks at the sector to see if its that data, and the signature will identify this, the other section, 4 max primary partitions, 16 bytes information is provided to the partition, which is 4x16 is 64 bytes which is referred to the partition table, those 64 bytes tell exactly how the database is partitions, how big where to start and all that, 446 is the third and its 512 all together, the last part is the program that tells the computer what to do, this makes use of some data where the loader is located, otherwise where the operating system is actually located, after it is done it will pass control to the boot loader,

Program Partition
Bootloader

After you initiate the bootlaoder it boots into the operating system, its below the spindles, another thing we should know, the processor can only execute instructions from the memory you can never have data go directly to the processor, memory to processor first, once we start booting the operating system otherwise known as the kernel in Linux, once it is loaded in memory then it goes into the processor, then the processor starts running the operating system, once it starts running, theirs a particular utility the first utility initiates all the other utilities, this is called the INIT every command that is dropped into memory to be in the processor there is a PID number and the first one is obviously PID01, this utility will load all utilities you need, print, telnet, everything loaded by the INIT utilities, one of that that is loaded by INIT is called the Getty, any time you see to tty you are referring to terminals, the

Getty utility - almost like a radar that scans all the terminals all the time , it is looking for if anyone is trying to use the terminal, system, as soon as it detects this it allows them to type in,
ex: user name and password you hit the return immediately

At that point the getty utility will pass control to another utility, called the

Logon utility - this utility does the checking you are who you say you are and you have an account on the system this will check into /etc/passwd which contains all the user names and check the password in /etc/shadow.

After the login it goes to the shell, now the shell is brought into the memory which is given a pid number and it starts running, once it starts running, that when you see the cursor on the screen when it produces the cursor on the screen it is ready to do what you want it to do, and the shell will actually take your command and before it runs it, it will interpret you command, (kernel executes the commands), the shell is learn the C language, the language were learning the Shell, you don’t need to know the Kernel, the language we need to know is the Shell language and what it does is it interprets what you type into the terminal and what the kernel understands its an interpreter, once of the advantages of the shell, it automatically interrupts anything you put in, it will interpret a line when it went in, you can actually read what the programmer wrote, the shell does the interpretation itself, it very important to understand the fact that when you execute a program or any command from the terminal the shell will interpret anything you write, the shell interprets EVERY COMMAND before its executed, it is looking for special characters and has a meaning, when you look at a command you should be able to interpret the commands in exactly the same way on how the shell interprets it. How to program and special characters and how exactly it interprets and some other features. Once it starts running, the shell will go through NINE steps, for every command it goes through NINE steps in a sequence and in each step looking for something specific, when its finished with the NINE steps it will then execute the command and will tell the kernel, this is the interpreted version of the command and the kernel will actually execute the command.

Here is an example of interpretation….

Ls a

This is what is typed in the command line, what is passed in the kernel looks like the exact same thing, because their was no special characters that the shell had to interpret,

Ls a??

The shell takes a look at the command, and it will search to match any files and will find 3 characters that must start with an A, We assumed it found ABC and a23, what is the interpreted version of this command, it will replace the >?< token with BC 23 this is the actual command that is passed=

Ls ABC A23

Copied into the memory then given a pid then executed and run by the processor, the kernel goes and looks for these two files and list the names, SHELL all interpretation.

He lying a little bit because the shell does actually run commands, but they are part of the shell and in memory and can be executed directly, but most of the commands must go through memory and go the kernel to execute.

Shell understands & interprets

Special characters we know about,
• ? --
• ---it says to shell zero or more of any character 0 >
• [ ….] -- 1-3or5square bracket one character, list of character inside the bracket > *?, < loose their special meaning. ! is not.
Understand the ? * ! []

More Examples:

Sort ?[!0-9,a-z]?[A-z]*

We are going to sort a number of files, and the number of files are going to match in that particular directory, it will be finding four or more characters.
First character is the name of any character
Second cannot be a number comma or a lower case letters
Third can be anything
Fourth it can be any letter to capital to lower case A LETTER
Fifth

^ this called file name expansion which the shell does all the time

All capitals are first then small, you can say 1-9 and not 9-1 goes through sequential sequence.

Variables to store data, global or shell variables that are assigned to every user, you are assigned those variables immediately, all shell variables have capital letters, that is one type of variable, another variable it a locally created variable, one u create.

BASH is the name of the shell you are using, and you look at the etc password file and locate the account on their the last item of the line you will see what shell if assigned to you, in matrix the BASH shell is the default shell that is assigned to all users, BASH=/bin/bash is exactly where it is located, var = variable .

What is the path variable used for, the kernel doesn’t know where the utility on the database it is relying on the shell where it is to execute and where it is located on the database it will go and search this particular variable for where its located, it goes into the PATH=/home/unx122/bin: colon is delimiter between directories, it will pass the directory name to the command. The PATH uses it to search where the command where it is located.

You prompt is located in PS1 this is what it looks like, tty =terminal, terminal logged is pts/4 and pts is via the communication network. If its tty/4 then its direct.

See the commands its going to be echo $variable, the $ says the following text is a name of a variable, the text following the dollar sign is the name of the variable when the shell looks atr this what it will do to interpret this it will go an replace the name of the variable with the contents of the variable, the shell interprets the command and comes up with a difference command.
The shell interprets $SHELL to $/bin/bash replacing the name of the variable with the contents of the variable.

You have to have the current directory in ur path or u cant run the program.

/etc/profile

Cal with no arguments tells you current month calander

If not sure use MAN cal [ ]option

The cat command comes from an old English word called concatenate means to join together

First Lecture DAT702

2007-09-06T13:37:00.000-07:00

DAT702 First Lecture
September 4, 2007
D group

INT213 we end up to a bit of a webpage to a database a webpage talking to databases and will connect to mysql, you will need to have.

We need a hard drive which is about 4gig of space

Mysql is on the internal machine Password mysql

We are going to get in to activities; Bin is the directory, in which we will be using all the time,

Mysql> \T doppy96.txt

All this is done so after every key stroke is logged

Two data bases u don’t touch info-schema and mysql, do not touch this.

Tell my sql what database to use, after we have created the database Harvey, you will have to type use harvey

Int – interger
Decimal
Varchar

We typed create table allan(mary int, sam varchar(30));

Oracale is case sensitive

Two fields Mary Int Sam is VarChar

Describe allan; which describes what we have just created

We close the log file by /t

Into the command prompt to load the database and browsed to the bin file this is to make or load backup files

Mysql – hlocalhost – uroot – pfrank banana > backupname.sqbac <---load

Mysqldump – hlocalhost – uroot – pfrank banana

DAT702 Second Lecture

Lab01
This is the concept of using MySql

Databases are series of data and quote “connected”. The easiest ways to visualize this is imagine three tables with headings of student, grades, courses, and there is a fields under each heading, student number is a unique, the stunum is the primary key unique and exist only once in the table, every thing below this primary key there is one record, you are one line and in one table only... WHY? Because if you want to update you want to update one table only, in order to build the school he has to build courses, theirs a primary key Code, grades is another field , stunnum primary key is linked to a foreign key Stunum in grades table, this saves you from being an idiot, what the link is saying you cannot put a student number in a foreign key constraint their must be a record in the students number this stops you from making stupid errors, the same thing goes for courses it will not put a code unless the record is in their. When creating a table and you connect it and you do not click Enforce the line does not do anything,
Don’t put spaces in you field names.
The most dangerous thing in a data base is an empty field.

SQLYOG

First Lecture WIN310

2007-09-06T13:25:00.000-07:00

WIN310 Fist Lecture

AD spending more time.

Today we will be covering IP addressing and subnetting, when we talk about tcp/ip we are talking about protocol that has been around for maybe 30 years and is the default protocol of the big network the web, we use the tcp/ip protocol this allows us to access resources and is on every platform, this is the same to where you are in the work….this is a standard. We are going to learn how tcp/ip works, we are going to learn the addressing scheme, every computer sending data throughout the network must have a unique id, it’s a unique address think you bloods DNA, if two computers have the same ip address and they are on the same network or subnet both computers will be down, think standards IEEE.

What is tcp/ip addressing?
This is a convention address of 32 bits, about 4 billion addresses, we are running out of address and are soon going to switch to IPV6. To subnet into 4 octets , each octet has a range of 8 bits in each octet coming to 32 bits. A part of the subnet will be assigned to the network address and the other to the post address, the network address is your area code, and the post address is the other number, Network and Host, 32 bits basically is infact today’s protocols that we use, but we will be moving to IPV6 very soon, IPV4 32, IPV6 128 bits its alphanumeric, its E128, the two protocols are compatible, and it is relative and very imperative, essential to have both protocols, imagine the millions of DNS servers and Host Servers, it needs to be upgraded to go to the versions, the two are compatible,

The 32 bits are divided into 5 different classes

Ip Classes: R N H
A - (N)(H)(H)(H) 1-126 126 16777216
B – (N)(N)(H)(H) 128-191 16384 65534
C – (N)(N)(N)(H) 192-223 2097152 254
D – Multi Cast Purposes 224-239
E – Is Experimental 240-255

Network Address C
Host Address A
127 is a class but is reserved for diagnostic purposes, basically a loop back.
Will not accept 224

Ask yourself why we have these class…identifies the network and its content, we said earilier that 32 bits the portion is Network the other is the Host Address,

Each number corresponds to a size, DO SUBNETTING ~MATH~

125.1.1.7

01111101.00000001.00000001.00000111

To get this the programmers have taken the highest octet and
8.8.8.8
This is what they have done to come up how many networks for the subnet they have taken the first bit of the octet and marked it with zero for class A

If we have 7 bits we have 2^7-2 = 126bits
If we have 14 bits we have 2^14 -2 =16384
If we have 21 bits we have 2^21-2 = 2097152
1111111._._._
A 0111111._._._
B 10111111._._._
C 11011111._._._

Every IP address must have the Subnet Mask is the piece that isolates the network from the host, there are three different masks

A 255.0.0.0
B 255.255.0.0
C 255.255.255.0

10.0.0.08
190.0.0.016
199.0.0.024
The bits are masked from the address ex: 8 bits are masked from the 10.0.0.0 address.

You can borrow from the hosts you will be able to subnet,

24.0.0.08
255.0.0.0
24.11111111.11111111.11111111

http://www.learntosubnet.com/