I have no clue how to use IP tables. Therefore, I could only try a limited number of firewalls. The top three easy-to-use firewalls I like are; Linux-Firewall, Guarddog, and Firestarter. I like Linux-Firewall (L-F) best. Linux-Firewall allows you to control which program(s) can access the web. Other firewalls don't do this. Instead, you end up opening or closing specific ports - which any program can use afterwards once opened. With L-F, you can open a port for a particular program and also restrict other programs from using it. The best feature L-F have is this; it will show you a pop-up window every time a new program tries to access the web, asking whether to allow or block it. This feature is vital to me. I threw a few firewall tests at each firewall and L-F worked to my liking. L-F can even block WINE applications by blocking it's "wineserver" client. Other firewalls failed to block WINE applications. L-F is not perfect, but it fulfilled my needs and has great potential (if they would continue to improve it, or make it open-source). At least try it, you might learn something useful.