Sean Carolan wrote: > What is confusing me is why my iptables rule is not working correctly. > TCPdump shows that the source is correct. Any ideas? try blocking tcp as well, most name servers listen on both tcp and udp. portal:~# netstat -anp | grep :53 | grep named tcp 0 0 10.10.10.1:53 0.0.0.0:* LISTEN 12978/named tcp 0 0 127.0.0.1:53 0.0.0.0:* LISTEN 12978/named tcp 0 0 216.39.174.24:53 0.0.0.0:* LISTEN 12976/named udp 0 0 10.10.10.1:53 0.0.0.0:* 12978/named udp 0 0 127.0.0.1:53 0.0.0.0:* 12978/named udp 0 0 216.39.174.24:53 0.0.0.0:* 12976/named nate