You can get these routers for little money and they are perfect for sitting in front of a firewall system with little hassle. (perfect for cisco, openwrt, iptables, pfsense etc)
this also works with DG934G routers as you can reflash them to DG834v3, loads on ebay branded Sky for £5-10
All you need to do is access a hidden option screen.
Open up the configuration in a browser and change
You can then select Modem and Apply.
Now setup the firewall that is behind the DG834G to connect via PPPoE on port1.
Reasons for having this setup: stop double NAT, firewall has a real external IP, no more DMZ or invisible proxy.
post taken from equk's miniblog