KMyFirewall is a KDE/Qt Programm that tries to provide an easy to use and comfortable GUI for the Linux "iptables" command. An easy to use plugin architecture allows fast and easy development of rule option extentions.
Guarddog is user friendly firewall management utility for KDE on Linux. It allows you to simply specify which protocols should be allowed between which groups of computers and requires no knowledge of port numbers or packets. Uses ipchains or iptables.