Like a lot of people I have at least one old pc kicking around in the loft, so I decided to put it to better use than gathering dust and install some linux on it! I have a home network and have never got round to buying a router for it, instead relying on pc to share the internet connection. This started out many years ago with an old 486 running or should I say crawling Windows 98, but all it had to do was route the traffic and it did remarkably well. A few years on and a couple more PC's on the network this had to be replaced.

Introduction.

What is a firewall?

Just as a building has a firewall and possibly a fire door to try to isolate a fire on one side of the wall, preventing it spreading to the other side, a computer firewall does much the same. However, it's not concerned with fires, but more to the point, unauthorised entry and use. It most commonly, sits between the computer and the Internet, although in complex networks, there can be others within the overall system.