[Bug 959037] Re: NM-controlled dnsmasq prevents other DNS servers from starting

[Thomas Hood]

Yes, the 127.0.1.1:53 solution works so long as dnsmasq and others are
run in bind-interfaces (or equivalent) mode.

NM-dnsmasq currently (12.04) listens at 127.0.01:53 which prevents
others from listening on either ALL:53 or lo:53, i.e., 127.0.0.1:53.
The new (12.10) behavior allows others to listen on 127.0.0.1:53, but
still doesn't allow them to listen on ALL:53.  Someone correct me if I'm
wrong.

> With bind, this is okay, mostly, because you can say to listen
> on everything for a particular interface

Are you sure?  I am only aware of named.conf's "listen-on { IP_ADDRESS;
}".  If there is a feature such as you describe then presumably named
binds ALL:53 and then filters according to the addresses on the
specified interfaces.

> (but then you can't listen on 127.0.0.1, because it's the same
interface as 127.0.1.1)

You don't listen on an interface, you listen on a socket --- an
address:port pair.  So when nm-dnsmasq binds 127.0.1.1:53, others can
still bind lo:53, i.e., 127.0.0.1:53.

A question about the NSS plugin idea. Will this work only for software
that uses glibc? What about alternative resolver libraries? They all
read resolv.conf, but do they all read nsswitch.conf too?  The djbdns
description

    http://cr.yp.to/djbdns/blurb/library.html

for one doesn't mention this.

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Title:
  NM-controlled dnsmasq prevents other DNS servers from starting

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