I have a debian server that acts as a router for a network, and I am planning on making it so I am able to block network access for certain computers, what do you think would be the best way to do it? I was thinking mac address filtering, although that could be spoofed. I was also thinking of IP filtering, but that could be avoiding just as easily. A few pages on google suggested doing something with arp tables, but im not sure how to go about doing that. Any help is much appreciated, thanks!
SnapOverflow
You're looking for layer 2 authentication, as in IEE 802.1X, on your switches or wireless access points. There's nothing that you can do on a gateway device (router, firewall, etc) to prevent layer 2 or layer 3 "spoofing". You need an authentication mechanism that operates on the layer 2 device to authenticate trusted devices.