Ethereal is a PacketSniffer.
It is now in pretty gtk2.
Although ethereal's help shows you many fields you can use to filter on, such as all the subfields of the various supported protocols, it doesn't give you any help as to how to set up a simple filter!
So, here are some simple examples:
Hides all SSH and ARP protocol packets
ssh && !arp
5 pages link to Ethereal:
