Linux

Good GTK inerface is available at http://icarus.autostock.co.kr/
And a good WWW interface at http://home.swipnet.se/rodac/doc/fwt.html

There are a few. The best is still writing your own rules by hand. But...there's a good one (the best IMHO) for kde at www.linuxberg.com. it's called kfirewall (it's even a RPM binary if you don't want to compile) . There are some others, just search the berg.

I have used both of these tools and like them both..

http://www.linux-firewall-tools.com/linux/firewall

http://home.nikocity.de/friedrichnet/FCT.htm

Find it on www.tucows.com

http://www.tectrip.net/arg/Fireman2.0.tar.gz
It was developed to be used with ipfwadm and icmpinfo. This manager is compatible with any Linux Kernel Version.

http://people.redhat.com/harald/firewall-config/
firewall-config is a configuration tool for IP firewalls and masquerading for RedHat 6.1 and higher.

http://home.nikocity.de/friedrichnet/Download.htm
This is an HTML based tool for the configuration of a firewall. It features automatic script-generation for IP-filtering commands (ipfwadm) on a firewall for multiple interfaces and any internet services. Visit the FCT Homepage for detailed setup instructions.

Good luck.