[Dnsmasq-discuss] dnsmasq not vending - replying with "Destination unreachable (Port unreachable)" until restarting the service

Simon Kelley simon at thekelleys.org.uk
Fri Apr 16 14:09:41 BST 2010


Arek Dreyer wrote:
> Hi - I'm running dnsmasq on a Mac OS X Server 10.6.3 build 10D673
> 
> I'm using dnsmasq solely to control which AD DCs my Mac OS X clients will try to use.
> 
> Things seem fine until clients start receiving "Destination unreachable (Port unreachable)"
> rather than a DNS answer.
> 
> Here's a screenshot from a wireshark capture: http://drp.ly/P8LcF
> 
> Stopping and starting the dnsmasq service fixes the issue. Any suggestions?
> 
> /var/log/dnsmasq.log is full of entries like this:
> Apr 15 11:30:33 dnsmasq[99]: query[SOA] local from 127.0.0.1
> Apr 15 11:30:33 dnsmasq[99]: forwarded local to 131.193.68.142
> Apr 15 11:30:35 dnsmasq[99]: query[SOA] local from 127.0.0.1
> Apr 15 11:30:35 dnsmasq[99]: forwarded local to 131.193.68.142
> Apr 15 11:30:52 dnsmasq[99]: query[SOA] local from 127.0.0.1
> Apr 15 11:30:52 dnsmasq[99]: forwarded local to 131.193.68.142
> Apr 15 11:30:56 dnsmasq[99]: query[SOA] local from 127.0.0.1
> Apr 15 11:30:56 dnsmasq[99]: forwarded local to 131.193.68.142
> Apr 15 11:30:57 dnsmasq[99]: query[SOA] local from 127.0.0.1
> Apr 15 11:30:57 dnsmasq[99]: forwarded local to 131.193.68.142
> Apr 15 11:31:09 dnsmasq[99]: query[SOA] local from 127.0.0.1
> Apr 15 11:31:09 dnsmasq[99]: forwarded local to 131.193.68.142
> Apr 15 11:31:09 dnsmasq[99]: query[SOA] local from 127.0.0.1
> Apr 15 11:31:09 dnsmasq[99]: forwarded local to 131.193.68.142
> Apr 15 11:31:39 dnsmasq[99]: query[SOA] local from 127.0.0.1
> Apr 15 11:31:39 dnsmasq[99]: forwarded local to 131.193.68.142
> 
> This is how the dnsmasq service is running:
> /usr/local/sbin/dnsmasq --keep-in-foreground --log-queries --log-facility=/var/log/dnsmasq.log
> 

A destination unreachable ICMP reply is normally generated by the kernel
when there is nothing listening on that port. The most likely reason for
that is that the dnsmasq process no longer exists. If that's the case
the problem changes into "find why the dnsmasq daemon is exiting".

HTH

Simon.



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