On 6 October 2015 at 00:46, James B. Byrne <byrnejb at harte-lyne.ca> wrote: > So, is there any convenient way to construct an IPTables rule to block > all IPs associated with a given Domain Name server? > You can use ipsets to block a large collection of IP addresses with netfilter. I block various problematic countries that way. The problem is getting _all_ the IP addresses associated with a DNS server. I don't think that is going to be easy/possible, unless that DNS sever has been badly misconfigured. K