I'm a router, switch, and firewall guy by trade, but I'm new to the linux world. I've been told that I can make a killer firewall out of a linux box, so I've now managed to get Debian installed in a machine with 4 nics in it. I wanna set up Internal, External, and DMZ networks.
Where's the first place I need to start.
I don't even know if there's a GUI tool I can use or if it'll be all CLI.
Where can I find some documentation about firewall configing a Debian box with multiple nics?