The purpose of this assignment is to learn about network protocols by using a “packet sniffer” to examine network traffic on the local area network in our lab.
For this assignment you will create a document called
R7.txt with a
section for each network protocol that you capture using the packet
sniffer. For this recitation we are using the
tcpdump packet sniffer.
Here is a sample
sudo tcpdump -A -i eth0 'tcp port https and host google.com' | tee log
Open your web browser and go to www.google.com.
| tee logdo?
Packet sniffers capture network traffic by listening to the interface on the local system, thus all LAN traffic is detected. Make sure you know how to specify the interface and how to dump an ASCII interpretation of the packets. The filtering mechanism in tcpdump is very useful for this assignment, since it allows the user to filter out unwanted traffic.
tcpdump to capture an HTTP request and reply from:
tcpdump to capture an HTTPS (did you see the ‘S’?) request and
reply from: https://www.cs.colostate.edu/~ct320/alphabet.txt
For each protocol in the following list, use
tcpdump to capture the
associated packets, and explain the purpose and size of each
request and reply:
tcpdump to find at least two other protocols that are ongoing in
the network lab. What is the purpose of the protocol and who is
generating it? What is the reply to the protocol from the local host,
and what is the purpose?
R7.txt to the TA for credit.