Linux.com: CLI Magic: Tcpdump
Jan 18, 2005, 00:15 (0 Talkback[s])
(Other stories by Joe Barr)
"Don't worry, I'm not going to try to turn you into to a network
security analyst or administrator. But if you're interested in
what's happening under the hood on your Internet connection, I'll
be happy to introduce you to an old and respected command-line
tool. Come on, pull that many-pixeled GUI quilt off of you and meet
me at the CLI for a look at tcpdump.
"Most distributions include tcpdump out of the box, and most
require that you run it as root. So as super user, simply enter
tcpdump at the command line. It will take the default values and
go, pumping out packets as they are received..."