53/TCP port unresponsive
Chris Buxton
cbuxton at menandmice.com
Fri Apr 3 16:38:42 UTC 2009
We've seen this repeatedly with our customers, usually evidenced by
slaves that stop refreshing and eventually expire the zone. It seems
to happen most on Mac OS X and Solaris, and less often (or perhaps
never) on Linux.
named just stops listening on the TCP port. If you execute "lsof -i:
53", you'll see that it's still listening on 127.0.0.1:53/TCP, but not
on some other interface. UDP seems to be unaffected by this.
The only solution we've found is to stop and restart named.
Chris Buxton
Professional Services
Men & Mice
On Apr 2, 2009, at 5:26 PM, Mark Koehler wrote:
> Greetings.
>
> We have 4 masters (rsync'd together) and a pair of load balancers
> each of which distributes queries to any of the 4. On the masters,
> we run Solaris 10 with BIND 9.5P1. Recently, one of the 4 stopped
> using TCP on port 53, but UDP traffic continued unaffected. What
> would cause the TCP port to stop? The port was unresponsive from
> the backside of the load balancers, and no DNS TCP packets came from
> the server either. Is there anything in BIND which would detect and
> block a potential DOS attack?
>
> Thanx,
> mrak
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