One side of iptables and netfilter that we haven't looked at very much yet, is the graphical user interfaces that are available for iptables and netfilter. One of the biggest problems with this is that netfilter is a very complex and flexible setup, that can perform the strangest of tasks. For this reason, it can become a very daunting task to create a GUI for netfilter.
Several persons and organisations have tried to create GUI's for netfilter and iptables, and some have succeeded better than others, while others have given up after some time. All have different reasoning behind their tries as well, so it isn't an easy task to show them all. However, this chapter is a small compilation of some of the GUI's for iptables and netfilter that may be worth looking at.
Firewall Builder, or simply fwbuilder, is an extremely versatile and powerful tool that can be used to build your own firewalls, or to maintain several firewalls for that matter. It can be used to create policies for several different types of firewalls, including iptables (Linux 2.4 and 2.6), ipfilter (freebsd, netbsd, etc), openbsd pf, and, with a module that must be bought, Cisco PIX.
Fwbuilder has, as you can see, a very big audience and is well taken care of and continues to be developed. It is run on a separate host system, where you create the policy files, and then copy them over and run them on the target system. It is able to handle everything from very simple rulesets to large and rather complicated ones. It has extensive abilities to handle different versions and installations of iptables, by configuration of which targets/matches are available on each host system, etcetera. The end result may be saved in an xml file, or a system parsable configuration file (e.g., the real firewall scripts).
You can see the configuration of the "firewall" in the above example, and the main menus of the whole fwbuilder system. fwbuilder can be found at http://www.fwbuilder.org.