There are many tools available to help you construct a complete firewall without intimate knowledge of iptables. For the GUI-inclined, Firestarter is quite popular and easy to use, and fwbuilder is very powerful and will look familiar to an administrator who has used a commercial firewall utility such as Checkpoint FireWall-1. If you prefer a command-line tool with plain-text configuration files, Shorewall is a very powerful solution to help you configure an advanced firewall for any network. If your network is relatively simple, or if you don't have a network, ipkungfu should give you a working firewall "out of the box" with zero configuration, and will allow you to easily set up a more advanced firewall by editing simple, well-documented configuration files. Another interesting tool is fireflier, which is designed to be a desktop firewall application. It is made up of a server (fireflier-server) and your choice of GUI clients (GTK or QT), and behaves like many popular interactive firewall applications for Windows.