[CentOS] Re: Iptables not blocking UDP port 53
scarolan at gmail.com
Thu Jul 10 20:51:53 UTC 2008
> Are you running tcpdump on the same machine that is doing the filtering?
> You do realize that tcpdump sees the packets as they come from the
> interface and before they are passed to the filter rules, right?
I had forgotten this important piece of information. Thank you for
pointing this out. The packets still seem to be getting through to
the BIND daemon, however, because I can still query the box from the
> Does the count field from "iptables -vnL RH-Firewall-1-INPUT" show
> your REJECT rules being hit?
Yes, the rule gets hit and it returns an answer to the DNS query
anyway. I saw it increment from 10 to 11 when I ran the query:
11 692 REJECT udp -- * * 10.100.1.1
0.0.0.0/0 udp dpt:53 reject-with icmp-port-unreachable
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