[Dnsmasq-discuss] prevent dnsmasq from releasing IPs

Neil Jerram Neil.Jerram at metaswitch.com
Tue Jan 26 16:03:47 GMT 2016


On 26/01/16 15:09, Stefan Priebe - Profihost AG wrote:
>> Am 26.01.2016 um 14:46 schrieb Simon Kelley <simon at thekelleys.org.uk>:
>>
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>>> On 26/01/16 13:42, Stefan Priebe - Profihost AG wrote:
>>> what about writing and sending kill 1 / HUP?
>>
>> No. The only only way to make that work would be to
>>
>> 1) Stop dnsmasq with SIGTERM
>> 2) modify the leases file
>> 3) restart dnsmasq
>>
>>
>> in that 
> Last idea isn't it possible to make the host static on add? If it is which file should I use to add the mac  hostname IP combination

FYI, at https://github.com/projectcalico/calico/issues/233 we have a
long trail about what we think is the opposite problem.  Namely, that
Dnsmasq will not reallocate an IP that should have been released, and
whose old IP/MAC mapping has been removed from the 'host' config file. 
As you'll see if you read that trail, we thought this was caused by a
problem in the delivery of the DHCP_RELEASE message to Dnsmasq, and
hence Dnsmasq retaining a record of the old lease in its internal data.

Based on that, I'd expect that if you deliberately did something to stop
the DHCP_RELEASE message from reaching Dnsmasq, Dnsmasq would then
retain the old lease (which I believe is what you're asking for).

However, that understanding does seem to be contradicted by what Simon
has said in this thread, and I would strongly assume that Simon is right
- but perhaps there might still be some hint or useful information in
that issue trail.

Regards,
    Neil




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