Just a heads up to say both tomato
http://polarcloud.com
and
DD-WRT
http://dd-wrt.com
have recently put out new versions that amoung other things close the DNS vunreablity
At the time of writing latest DD-WRT is 24sp1 and tomato is v1.21
Thought it might be usefull for the people here who use these excellent firmwares on their routers and haven't checked the respective sites recently.