On 11/10/13 16:37, Rick Jones wrote:
On 10/11/2013 07:16 AM, Simon Kelley wrote:
On 11/10/13 01:39, Rick Jones wrote:
I am still on the steep learning slope for dnsmasq. The manpage lists a
-l/--dhcp-leasefile option into which dnsmasq will store lease
information. I gather though that it will be updating that all the time
as leases come and go.
Is there a version post 2.59 where one can send dnsmasq a signal to
cause it to dump a copy of its current lease information to a file, but
without the continuous updates in normal operation?
No. there's a mode meant for use on flash filesystems that updates the
lease file less often, if that helps.
It might actually. I'll try to take a look at it.
See also this thread
http://lists.thekelleys.org.uk/pipermail/dnsmasq-discuss/2013q3/007555.html
From that I should take away that the lease file format is not fixed
and there but for the grace of the developers go I should I start
grubbing through it, yes? I can accept that.
More context about what youre trying to achieve would help.
What I would like to be able to do is "know" (make an informed guess)
which of the clients which could have a lease probably have a lease (or
probably do not have a lease), but in an environment where I might have
either rather busy dnsmasq processes, or a large number of individually
not very busy dnsmasq processes and want to minimize the storage load.
But I don't need to know all the time, just occasionally and not
necessarily on a schedule and not necessarily all the dnsmasq processes.
So, I figured some sort of "dump your current leases" feature would
satisfy that.
I cannot really rely on the clients being willing to respond to the
likes of ping, they may only respond to things they've initiated
themselves. I also do not have other access to the clients (eg their
console). So, all I can think of presently is trying to ask the dnsmasq
process(es) what it believes its active leases happen to be.
thanks,
rick
BTW, sorry about botching the last part of the subject there.
You could achieve the two aims "minimise storage load" and "know about
dnsmasq leases" by implementing the lease database in some sort of
lightweight database. Dnsmasq is designed so it can be without a lease
file completely. At startup you prime the in-memory copy of the lease
database via a DHCP-script "init" call, and then whilst dnsmasq is
running is makes calls to the DHCP script as the data changes which can
be used to update the database.
Cheers,
Simon.
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