Sniffit is a network sniffer for TCP/UDP/ICMP packets. 

Sniffit produces very detailed technical details about the packets flowing
through your network (SEQ, ACK, TTL, Window, ...) and also packet contence
in different formats (hex or plain text, ...)

See the Sniffit home page at
http://reptile.rug.ac.be/~coder/sniffit/sniffit.html
FAQ at 
http://reptile.rug.ac.be/~coder/sniffit/sniffit-FAQ.html
secondary page at
http://reptile.rug.ac.be/~wvdputte/sniffit_addicts_anonymous/

- Adam McDougall
mcdouga9@egr.msu.edu