CS 176B - Network Computing
    Homework Assignment #4
    Due March 7 ( In Class )

    (TA: Kamil Sarac - ksarac@cs)

Assignment Overview

This assignment will help you to learn to understand what is going on in the network. This is something of a difficult task because network protocol designers have worked hard to provide so much abstraction to the higher layer protocols. Never fear though, there are tools that we can use.

Assignment Details

The goal of the assignment is to examine real protocols in use and understand the communication that takes place in a network by examining the bits that flow across a network segment.  The command is snoop; however, it requires root privileges to run. This is a good thing because it should be hard for anyone to look at any and all packets on the network! So, I've done the snooping and created a dump file. Take the hw4-source file and use it as the source file for snoop (HINT: do a man snoop and look at how to use the -i option... you can do this without having root). You will also want to use some of the other options that come with snoop. Pay attention to options which give you the most information about packets. Some of the questions below will be about material that we have not, and will not be covering in class. You'll have to use Tanenbaum as a reference to answer them and be prepared to ask questions in the discussion section.

 A note about grading: a key to a good grade will be your ability to communicate that you understand most everything about the packet trace. This implies, as usual, a clear, concise write-up! The questions below are designed to help you find the most interesting aspects of the trace, but they are by no means exhaustive. There will be other interesting results that you should find. Also the more you investigate and understand the better you will do.

 Your write-up for this assignment can take any form you like. The most straightforward is to simply answer each question though I would strongly recommend a more creative approach. The reason is that the questions are purposely haphazard. My suggestion is to first answer the questions, understand what is going on in the trace, and then create a description of the session filling in the details as necessary.

Here are the sample questions:

        General Questions

        About  traceroute:

        About HTTP session: