Groinc is a simple text-mode sniffer. You could use complexe filters for datalink,network and transport layer protocols and data. There is a regex filter for layers over the transport layer. You can save or load your captures in a file. You have the choice between a lot of type of display (from simple to very detailed).
A lot of protocols are available by default.
Groinc released under GNU General Public License V2.
You can download Groinc here.
You can take a look on the source code here.
You can contact the development team using this mailing list groinc-devel@nongnu.org.
You can get support using this mailing list groinc-help@nongnu.org.
You can submit a bug using the mailing list groinc-bugs@nongnu.org or using the bug tracker.
Copyleft 2006,2007 Luc Sarzyniec