Readings from the text book:
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Module 1 is essentially the first three sections from the text, with some supplementary material. The goal is to familiarize you with the world of Computer Networks,its key players and some of the tools of the trade. Pay special attention to understanding the difference between Packet Switching with message segmentation and Circuit Switching, and why Packet Switching is preferred in most Internet as well as telephony applications - see section 1.3 of the text. |
See these supplementary notes. Try this exercise. |
| Unix tools These are common tools used by network administrators. You should become familiar with them. |
All registered students must have automatically obtained an account on the cs lab main server, wyvern.cs.newpaltz.edu. Login to your cs account and try these commands in a terminal window. You may also try these on any linux/MacOSX terminal window. Some commands like traceroute may need root permission to run on some systems. ping shell.newpaltz.edu traceroute www.yahoo.com netstat -an netstat -rn We will learn how to read and interpret the output from these tools later in the course There are newer and improved versions of these tools, which may not be available on wyvern, but comes with many standard linux distributions. Some of these are: ss ip mtr tracepath |
ping simply sends a stream of packets (echo requests) to another host, which it echoes back (echo replies). The round-trip time of packets and other statistics are reported by the ping program. Sometimes, a host may not echo back ping packets; sometimes a router on the way may intercept echo request/reply packets - this happens when you try to ping a campus machine from outside the campus. Bottom line is that ping command may not always work for a variety of reasons.
traceroute traces the route from your host to another host. netstat is very versatile. Do man netstat at the unix prompt to check man pages for this command. netstat is available on Windows machines too. On most Windows machines, you can open a Command Window and execute netstat with appropriate switches. |
| Wireshark | Wireshark is a network packet capture and analysis tool available for Linux/Unix and Windows platforms. It can be freely downloaded from http://www.wireshark.org With Wireshark, you can capture network packets on any network interface on your computer. You can save these captured packets in a file for later analysis. Wireshark also comes with its own tools for analysis of the captured packets. A goal of this course is to be able to look at captured network packets and understand their structure and function. Please download and install Wireshark on your machine. It will be quite useful for this course, as well as for other purposes. |
Wireshark is perhaps the best network packet analyzer around. It has a pretty easy user interface. See documetation at http://www.wireshark.org/docs |
| You should either already be familiar with the terms listed in the table to the right, or you should become familiar with them. |
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A brief summary of these terms |
| Internet-related web sites |
Check the following URLs:
www.faqs.org --- Searchable list of RFCs. A very useful site. Following is a very incomplete list of organizations that set standards for the Internet as well as other stuff. Please spend a few minutes exploring each of these organizations.
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Look these up:
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