Forcing network clients to use open dns

RouterOS Beginner Basics
1

Hello
Is it possible to force network clients to use opendns? I have setup opendns servers on my rb with success, but my clients can get around it by entering a custom dns like 8.8.8.8 in their network adapter settings. Any help would be much appreciated.

2

/ip firewall nat add chain=dstnat action=redirect in-interface= dst-port=53 protocol=tcp to-ports=53
/ip firewall nat add chain=dstnat action=redirect in-interface= dst-port=53 protocol=udp to-ports=53-Chris

3

Thanks for the response. I tried what you suggested without success. I can still manually enter a DNS server and get past. I tried this setup and it seems to work. Not sure if it is correct. What do you think?

add chain=dstnat action=dst-nat to-addresses=208.67.222.123 to-ports=53 protocol=udp dst-port=53