If you need to capture data into and out of a computer you can download and run Wireshark. But if you need two way chatter (both sides of the conversation) you will either need to use a spanned port on a switch or use a port aggregator. Then start your Wireshark trace and you can capture and analyze your network traffic.
Do you have any tips or tricks regarding Wireshark? If so we would love to hear from you in the comments below.
Wireshark can be grabbed from http://www.wireshark.org