resolv.conf and a non-standard port

[Victor Sudakov]

Bert Kiers wrote:
> >>
> >>> How can I configure the resolver to use a DNS server with a
> >>> non-standard port? 
> >>>
> >>> I have a host running an authoritative-only server (nsd) for the
> >>> world, and I want to run local unbound for the host itself (can't use
> >>> nsd for recursive queries).
> >>>
> >>> Unbound can listen on a non-standard port, but how do I configure the
> >>> host to use the DNS server at 127.0.0.1:5353 ?
> >>
> >> I think it will be more simple to have nsd and unbound listen on
> >> different IP-adresses, like unbound on 127.0.0.1 and nsd on the external
> >> IP-address.  Then put 127.0.0.1 in resolv.conf
> > 
> > That's how I have configured it now, but this solution has a major
> > drawback: you need to specify the IP address explicitely in
> > /var/unbound/unbound.conf which can be inconvenient in some
> > situations.
> > 
> > So it's a workaround, but by no means "more simple."
> 
> What happens when you let unbound listen on 127.0.0.1 and nsd on *
> (a.k.a. 0.0.0.0)?  That may work because 127.0.0.1 is more specific.
> Maybe the startup order of the daemons is important then.


# sockstat -l | grep unbo
unbound  unbound    448   3  udp4   127.0.0.1:53          *:*
unbound  unbound    448   4  tcp4   127.0.0.1:53          *:*
unbound  unbound    448   5  stream /var/run/local_unbound.ctl
# service nsd start


[2017-08-21 20:01:16.335] nsd[56380]: notice: nsd starting (NSD 4.1.17)
[2017-08-21 20:01:16.336] nsd[56380]: error: can't bind udp socket: Address already in use
[2017-08-21 20:01:16.336] nsd[56380]: error: server initialization failed, nsd could not be started


-- 
Victor Sudakov,  VAS4-RIPE, VAS47-RIPN
AS43859