Network sniffer

I need an application that can log all packets leaving my computer on a certain port. I found this program CommView, but the evaluation version is not fully functional. Anybody know some good freeware?

Forgot to say it's for the Windows platform.

You could just get a Personal Firewall and configure it to log on whatever port you'd like.

I had a similar question - I think it was Terr that pointed me to Ethereal. Works like a charm.

Yesss! Exactly what I was looking for! Thanks!:D