In the spirit of Upside-Down-Ternet, I thought I'd play some pranks with all the neighbours squatting on my wifi. I recently installed OpenWrt on my Linksys, which has a very nice Linux distro: It comes with all the features you'd expect of a Wifi router, plus all the best Linux tools: SSH, a package and repository system with comprehensive tools, and of course iptables.
And here we go:
# Accept my machines
iptables -t nat -A PREROUTING -m mac --mac-source 00:12:34:56:78:90 -j ACCEPT
iptables -t nat -A PREROUTING -m mac --mac-source 00:ab:cd:ef:01:23 -j ACCEPT
# Everybody else gets Slashdot for HTTP
iptables -t nat -A PREROUTING -p tcp --dport 80 -j DNAT --to-destination 188.8.131.52
iptables -t nat -L PREROUTING
You will notice that in the end I opted to only forward port 80. There were some issues with going for everything, presumably because some DHCP or DNS traffic is affected. But at least my neighbours can read Slashdot!