[Bug 959037] Re: NM-controlled dnsmasq prevents other DNS servers from running, yet network-manager doesn't Conflict with their packages

[Thomas Hood]

Simon:
> If you can make #2 happen without breaking things, that would seem to be worth doing

Indeed, primum non nocere.  Standalone dnsmasq works fine in the absence
of NM+dnsmasq and vice versa and this must continue to be the case when
we are done.  :)

> I guess the main problem is that you need dnsmasq 2.61

As this issue has low importance I imagine it will only be fixed in
quantal?

Simon:
> Further to #2 and getting dnsmasq support. I found a bug last night
> that means that dnsmasq --listen-address=<ip addr> where <ip addr>
> is not on an interface, will listen on port 69 of <ip addr> even if 
> tftp is not enabled

I just changed the lines in NetworkManager C code:
s/127.0.0.1/127.0.0.2/.  With this change nm-dnsmasq does indeed not
listen... unless address 127.0.0.2 is added to lo.  But then standalone
"dnsmasq --bind-interfaces" won't start unless that address is removed
from lo again.

Once they have both been started in this way they both work ---
standalone dnsmasq forwarding to nm-dnsmasq and the latter forwarding to
the upstream nameservers.

The reason they cascade in this order is that dnsmasq registers
127.0.0.1 under the name "lo.dnsmasq" which has a high priority
according to /etc/resolvconf/interface-order; it thus appears in
resolv.conf.  NM registers 127.0.0.2 with resolvconf and this is given
to standalone dnsmasq by /etc/resolvconf/update.d/dnsmasq as its
forwarding address.  Nm-dnsmasq is given the addresses of the upstream
nameservers by NM in /var/run/nm-dns-dnsmasq.conf.

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Title:
  NM-controlled dnsmasq prevents other DNS servers from running, yet
  network-manager doesn't Conflict with their packages

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