Blocking other DNS

[Chains]

Hi,
Looking to setup OpenDNS, but wondering how I can block people from using their own DNS servers that they can setup in the ip config files.

Running merlin on ac66u.

I think i need to block port 53 except for the opendns, but unsure how to implement that in the router.

 

[RMerlin]

Use the Wiki, Luke... <rasp>

https://github.com/RMerl/asuswrt-merlin/wiki/Iptables-tips