[Dnsmasq-discuss] Why is dnsmasq reading /var/run/dnsmasq/resolv.conf twice when it starts up?
Dan Williams
dcbw at redhat.com
Thu Oct 3 20:48:30 BST 2013
On Thu, 2013-10-03 at 17:05 +0100, Chris Green wrote:
> On Thu, Oct 03, 2013 at 04:42:59PM +0100, Simon Kelley wrote:
> > On 03/10/13 16:29, Chris Green wrote:
> > >When I start dnsmasq I see the following in syslog:-
> > >
> > >Oct 3 16:09:03 revo dnsmasq[2819]: started, version 2.63rc6 cachesize 150
> > >Oct 3 16:09:03 revo dnsmasq[2819]: compile time options: IPv6 GNU-getopt
> > DBus i18n IDN DHCP DHCPv6>
> > >Oct 3 16:09:03 revo dnsmasq-dhcp[2819]: DHCP, IP range 192.168.1.80 --
> > 192.168.1.150, lease time 1h
> > >Oct 3 16:09:03 revo dnsmasq[2819]: using local addresses only for domain zbmc.eu
> > >Oct 3 16:09:03 revo dnsmasq[2819]: reading /var/run/dnsmasq/resolv.conf
> > >Oct 3 16:09:03 revo dnsmasq[2819]: ignoring nameserver 192.168.1.2 - local interface
> > >Oct 3 16:09:03 revo dnsmasq[2819]: using nameserver 194.72.0.114#53
> > >Oct 3 16:09:03 revo dnsmasq[2819]: using nameserver 212.159.6.10#53
> > >Oct 3 16:09:03 revo dnsmasq[2819]: ignoring nameserver 127.0.0.1 - local interface
> > >Oct 3 16:09:03 revo dnsmasq[2819]: using local addresses only for domain zbmc.eu
> > >Oct 3 16:09:03 revo dnsmasq[2819]: read /etc/hosts - 12 addresses
> > >Oct 3 16:09:03 revo dnsmasq-dhcp[2819]: not giving name revo.zbmc.eu to
> > the DHCP lease of 192.168.>
> > >Oct 3 16:09:03 revo dnsmasq-dhcp[2819]: not giving name revo to the DHCP
> > lease of 192.168.1.148 be>
> > >Oct 3 16:09:05 revo dnsmasq[2819]: reading /var/run/dnsmasq/resolv.conf
> > >Oct 3 16:09:05 revo dnsmasq[2819]: ignoring nameserver 192.168.1.2 - local interface
> > >Oct 3 16:09:05 revo dnsmasq[2819]: using nameserver 194.72.0.114#53
> > >Oct 3 16:09:05 revo dnsmasq[2819]: using nameserver 212.159.6.10#53
> > >Oct 3 16:09:05 revo dnsmasq[2819]: ignoring nameserver 127.0.0.1 - local interface
> > >Oct 3 16:09:05 revo dnsmasq[2819]: using local addresses only for domain zbmc.eu
> > >
> > >Why is it doing everything twice?
> > >
> > Probably because whatever populates /var/run/dnsmasq/resolv.conf
> > alters the modification time just after it starts dnsmasq.
> >
> That makes sense I guess!
While I don't know how Ubuntu has configured it, NetworkManager spawns a
private instance of dnsmasq to handle local caching nameserver if you've
configured that in /etc/NetworkManager/NetworkManager.conf. Otherwise,
it might be some interaction between resolvconf (a resolv.conf manager
that Debian-based systems use) and dnsmasq that's set up outside
NetworkManager.
Dan
> > >
> > >While I'm about it, what creates/populates /var/run/dnsmasq/resolv.conf?
> >
> > We need more context to have a hope of answering that.
> >
> OK. As you may gather I'm playing about a bit with my dnsmasq
> configuration on the server machine at 192.168.1.2. It's a small Acer
> Revo machine running Ubuntu 12.10.
>
> I recently changed ISP and thus needed to change the DNS servers that
> dnsmasq uses upstream of itself. That was my first problem because I
> couldn't find where these are set. I *think* I have found it now,
> they're in the files in /etc/NetworkManager/system-connections. I have
> in "Wired connection 1":-
>
> [802-3-ethernet]
> duplex=full
> mac-address=00:01:6C:6C:C7:9B
>
> [connection]
> id=Wired connection 1
> uuid=2262541a-2106-4e4d-b2b7-ab631dddcbf1
> type=802-3-ethernet
> timestamp=1361810287
>
> [ipv6]
> method=ignore
>
> [ipv4]
> method=manual
> dns=127.0.0.1;212.159.6.9;212.159.13.49;
> dns-search=zbmc.eu;
> addresses1=192.168.1.2;24;192.168.1.1;
> may-fail=false
>
> Presumably (relating to the other thread) I can add a 'manual' ipv4
> section like the one above to the file in the same directory that
> relates to the wireless interface.
>
> The "doing things twice" was just something I noticed, probably
> NetworkManager is doing things at boot time and happens, as you said, to
> change the file just after dnsmasq reads it. Not a big issue really, it
> only happens at boot time I think.
>
>
> Hopefully all these things are resolved now and I can leave the list in
> peace. However I did have one issue where, after rebooting the dnsmasq
> server machine nothing worked at all (i.e. no DNS or DHCP) until I
> manually restarted dnsmasq itself. I'll try it all again, carefully,
> and see if the same happens again.
>
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