Go to https://www.wireshark.org/ and you will see the download link on the home page. Click and go with the default settings to load onto your machine. This is free software. You will use the software for the following lab. This is the video to walk you through downloading wireshark onto your computer.

YouTube Video: "Downloading Wireshark" Duration: 03 minutes 06 seconds Link: https://www.youtube.com/watch?v=NCeahhvUCbQ Download Transcript: Downloading Wireshark

Using wireshark, carry out the following analyses:

1. Identify the TCP options that have been used on the TCP connection

2. Try to find explanations for the evolution of the round-trip-time on each of these TCP connections. For this, you can use the round-trip-time graph of wireshark, but be careful with their estimation as some versions of wireshark are buggy

3. Verify whether the TCP implementation used implemented delayed acknowledgements

4. Inside each packet trace, find:

one segment that has been retransmitted by using fast retransmit. Explain this retransmission in details.

one segment that has been retransmitted thanks to the expiration of TCPs retransmission timeout. Explain why this segment could not have been retransmitted by using fast retransmit.

5. Wireshark contains several two useful graphs: the round-trip-time graph and the time sequence graph. Explain how you would compute the same graph from such a trace.

6. When displaying TCP segments, recent versions of wireshark contain expert analysis heuristics that indicate whether the segment has been retransmitted, whether it is a duplicate ack or whether the retransmission timeout has expired. Explain how you would implement the same heuristics as wireshark.

7. Can you find which file has been exchanged during the transfer?