WireShark (aka Ethereal)

Same developers, same code, different name. The Ethereal network protocol
analyzer has changed its name to Wireshark.

Wireshark's powerful features make it the tool of choice for network
troubleshooting, protocol development, and education worldwide.

Wireshark was written by an international group of networking experts, and is
an example of the power of open source. It runs on Windows, Linux, UNIX, and
other platforms.
