Router domain blocking
I am using a slackware box as a router (2 nics).
Playing with DD-WRT on a Linksys router, I noticed that it offers the ability to block certain domains. I'm not clear on the exact function of that blocking, but I assume that it looks up the DNS entry(s) for the user listed domains, and then does something.
Does anyone here know what the mechanism is for doing this?
Even better, is there a CLI string which will accomplish the same or similar thing on a system with iptables?