Lab 1 exercises

The following exercises are to familiarize you with the Ethernet PDU as well as a general introduction to packet sniffers. The following commands may be necessary in completing the following steps: hostname, ifconfig, ethereal and/or tcpdump. If any of these commands are unfamiliar, refer to the man page for that command.

Note: the ethereal sniffer sits on top of tcpdump and provides a nice window based UI for you to examine network packets. Since it sits on top of tcpdump, several of the command inputs are the same, such as the packet filters. This will require you to be familiar with tcpdump (or at least have access to the tcpdump man pages. You have been warned!)

1. Log on to your machine (using the correct partition, lone-day, ltwo-evening) as root and start an X window session.

2. Start at least 1 terminal window (you may find use for more).
3. Determine and make note of the host name of your machine.
4. Determine and make note of the hardware addresses of your machine.
5. Start the sniffer of your choice (ethereal or tcpdump), and take some time to become familiar with the components of the sniffer. If display size is an issue, try [alt] m to resize.

6. Start capturing packets moving along the network (you might want to start a browser application and enter a URL) for a short period, then stop the capture.
7. Carefully view the results, paying specific attention tothe layer 1 and 2 frame data for several communication exchanges.
8. NOTE: If you choose to print, ALWAYS USE PRINT PACKET, NOT PRINT!