Wireshark was designed for quickly capturing, then analyzing network packets and displaying detailed information about them.
In the past, this type of tool was either costly, proprietary, or both. However, all that has changed now, and this networking tool is a great example. Wireshark is perhaps one of the best Open Source packet analyzers available today. It allows you to troubleshoot network problems, examine security difficulties, debug protocol implementations, and learn network protocol internals.
Wireshark is available for UNIX and Windows; it allows you to capture live packet data from a network interface and then display them with detailed protocol information. You can also import/export packet data in conjunction with many other capture programs.