www.firestarter.org ? If that doesn't work head over to
www.freshmeat.net and search for firestarter.
AFAIK *most* of the firewalls will use iptables to do most of the blocking, most of the programs just put a nice face on this to help you see what you are doing.
For ultimate security, check out:
www.demarc.com and the program is called puresecure. There is a free version for personal use on linux.
Cool