Okay, before I start to tell you how great Portsentry is and how you to can install and use it, I'm going to give two pieces of advice. First, read this all the way through prior to doing ANYTHING! This is especially true for my fellow Debian users. There is a special treat near the end for you, but this is advice everyone should follow. Second, while Portsentry is an excellent security application, having it is not an excuse to be lazy on security. You can't put Portsentry on an entirely insecure box with everyone's worst security holes and expect it to be secure. It isn't happening. That said, I will continue.