[CentOS] Help with iptables rule for blocking UDP port 53

[Sean Carolan]

On Tue, Jul 15, 2008 at 11:55 AM, nate <centos at linuxpowered.net> wrote:
> 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.

I do have a rule for blocking TCP, forgot to mention that.  You can
see from my tcpdump output above that the inbound packet is UDP
though.  I wonder why iptables doesn't block it even with this rule?