I want to block all incoming requests on my two DNS servers APART FROM certain IP addresses e.g. IP of 18.104.22.168 will be allowed to make requests but NOBODY else will.
How do you do this with iptables?
This is very simple with iptables:
I'll assume your INPUT chain has no default DROP rule at the end, or you'll have to work around that:
Simply remove the two bottom rules if you have a default DROP policy. If you have a default DROP rule at the bottom of your chain, you'll have to insert (