[Dnsmasq-discuss] Serial loosed after restart

[Christian Ruppert]

Hi Simon,

it's a VM with no real HW-Clock, that is correct. Using seconds since 1970 would
be ok but the serial starts with "1" when dnsmasq has been (re-)started:

# ps aux | grep dnsmasq
dnsmasq  17460  0.0  0.0  30296   956 ?        S    Sep25   0:06
/usr/sbin/dnsmasq -x /var/run/dnsmasq/dnsmasq.pid -u dnsmasq --local-service

So it's running since yesterday (2014/09/25) and has currently a serial of:
# dig -t SOA +short ipmi.rz.babiel.com @127.0.0.1 -p 5353
. . 4947 1200 180 1209600 600

Now if I restart dnsmasq:
# /etc/init.d/dnsmasq restart
[ ok ] Restarting DNS forwarder and DHCP server: dnsmasq.
# dig -t SOA +short ipmi.rz.babiel.com @127.0.0.1 -p 5353
. . 1 1200 180 1209600 600

It starts from 1 again.

Re "--auth-soa":
I tried "auth-soa=20140926001" but:
# dig -t SOA +short ipmi.rz.babiel.com @127.0.0.1 -p 5353
. . 2961056818 1200 180 1209600 600
So that's not the serial that I specified. Anyway, after some time it increased
to 19, 20, ... and after a restart it was again at "2961056818". So using
"auth-soa" won't help :(

On 09/25/2014 11:04 PM, Simon Kelley wrote:
> On 25/09/14 10:39, Christian Ruppert wrote:
>> Hey Guys,
>>
>> I use the auth-zone, auth-sec, auth-peer features and I noticed that dnsmasq
>> looses its actual SOA resp. serial during restarts and thus it started again
>> from the beginning (1). All slaves were rejecting the changes because of that
>> serial mismatch. E.g. the slaves all had "34286" and dnsmasq started from "1" again.
>> It would be really good to save the serial in the lease file or somewhere else
>> and re-use it afterwards to avoid such problems. Is that a bug or was it on purpose?
>>
> 
> It's supposed to work like this:
> 
> The serial number starts as the time (seconds since 1970) when dnsmasq
> is started. Therefore stopping and restarting dnsmasq should _increase_
> the serial.
> 
> My guess is that you're using a platform which doesn't have a hardware
> real-time-clock, and so it's idea of the time gets reset whenever it's
> rebooted. Even if it uses NTP to get a good value of the time, this will
> happen after dnsmasq has started.
> 
> 
> You can set the initial serial number when starting dnsmasq using the
> command-line argument (or config option.)
> 
> --auth-soa=<serial number>
> 
> so you could implement something like the behaviour you want by keeping
> the serial in a file, incrementing it each time dnsmasq starts, and
> feeding it to dnsmasq via the command line. Shell scripting to do this
> left as an excercise....
> 
> 
> Cheers,
> 
> Simon.
> 
> 
> 
> 
> _______________________________________________
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> Dnsmasq-discuss at lists.thekelleys.org.uk
> http://lists.thekelleys.org.uk/mailman/listinfo/dnsmasq-discuss
> 

-- 
Mit freundlichen Grüßen,
Christian Ruppert
Systemadministrator

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