Your Network's Secret Life, Part 5
Ethereal is available for a variety of platforms and is distributed free under the GPL. While it is technically beta software, you'll be amazed at how useful you'll find it.
Ethereal is another of those programs that requires the libpcap packet capture libraries. We've talked about this one before, most recently in the third part of this series. If you don't already have it, check out the libpcap web site at https://www.tcpdump.org/. You'll also need GTK+ (likely to be already installed on your system). GTK+ is available from https://www.gtk.org/.
The link for this article located at Linux Journal is no longer available.