dnsmasq won't start

[Patrick O'Callaghan]

On Mon, 2016-01-25 at 14:37 +0100, Tom H wrote:
> On Mon, Jan 25, 2016 at 2:30 PM, Patrick O'Callaghan
> <pocallaghan at gmail.com> wrote:
> > 
> > For some reason I'm getting this:
> > 
> > $ systemctl status dnsmasq
> > ● dnsmasq.service - DNS caching server.
> >    Loaded: loaded (/usr/lib/systemd/system/dnsmasq.service;
> > enabled; vendor preset: disabled)
> >    Active: failed (Result: exit-code) since Mon 2016-01-25 13:27:16
> > GMT; 1s ago
> >   Process: 3502 ExecStart=/usr/sbin/dnsmasq -k (code=exited,
> > status=2)
> >  Main PID: 3502 (code=exited, status=2)
> > 
> > Jan 25 13:27:16 bree systemd[1]: Started DNS caching server..
> > Jan 25 13:27:16 bree systemd[1]: Starting DNS caching server....
> > Jan 25 13:27:16 bree dnsmasq[3502]: dnsmasq: failed to create
> > listening socket for port 53: Address already in use
> > Jan 25 13:27:16 bree dnsmasq[3502]: failed to create listening
> > socket for port 53: Address already in use
> > Jan 25 13:27:16 bree systemd[1]: dnsmasq.service: Main process
> > exited, code=exited, status=2/INVALIDARGUMENT
> > Jan 25 13:27:16 bree systemd[1]: dnsmasq.service: Unit entered
> > failed state.
> > Jan 25 13:27:16 bree systemd[1]: dnsmasq.service: Failed with
> > result 'exit-code'.
> > 
> > Can't figure out what is sitting on port 53 (the DNS port). I'm not
> > running bind.
> 
> Unbound?
> 
> NetworkManager? (check the "dns=" line in
> "/etc/NetworkManager/NetworkManager.conf", if it exists.)

There is no such line, however in the NM config options I do have
nameservers set to 127.0.0.1,192.168.1.254 (my router) and normal non-
local DNS queries work. Queries from elsewhere on my LAN which are
configured to point at this machine just timeout.

> Check the listening ports with ss.

See my reply to Tim in this thread.

poc