A firewall is often the heart and soul of desktop security. With a firewall, you can block or allow traffic in and or out of your computer. Of course, it's the incoming traffic that you need to be most concerned about. You don't want some ne'er do well to see port 25 open on your PC and use it as a way to get into your system and do bad things. To that end, your firewall is the way you shut those ports down. Back in the old days, the Linux firewall was a very complicated
