[Dnsmasq-discuss] Bug list and DHCP test harness

[Tom Isaacson]

On 16 May 2015 at 08:16, <dnsmasq-discuss-request at lists.thekelleys.org.uk>
wrote:

> Date: Fri, 15 May 2015 20:53:16 +0100
> From: Simon Kelley <simon at thekelleys.org.uk>
> To: dnsmasq-discuss at lists.thekelleys.org.uk
> Subject: Re: [Dnsmasq-discuss] Bug list and DHCP test harness
> Message-ID: <55564EAC.3070006 at thekelleys.org.uk>
> Content-Type: text/plain; charset=windows-1252
>
> On 15/05/15 17:22, Tom Isaacson wrote:
> > We have a device (not made by us) that's using dnsmasq V2.46 and
> > occasionally we've seen a few problems with it - DHCP renews being sent
> out
> > every minute, different IP address being provided on renew. Is there a
> bug
> > list for dnsmasq that shows what bugs existed in old versions? I know
> about
> > the changelog but it's not very easy to see what bugs existed when.
>
> The changelog is as good as it gets, I'm afraid. The git history doesn't
> go back that far. The only other resource is my memory, which is faulty
> and partial, as you might imagine. However I think I'd remember if there
> was ever a bug of that nature (changing IP address), and I don't
> remember such. The timing of DHCP renews is down to the client, which
> implies a client problem for the "renew every minute" problem.
>
> >
> >
> > The second problem I mentioned - different IP address being provided on
> > renew - has exposed a bug on our device. We think we've fixed it but I
> was
> > wondering if there's a DHCP server test harness we can use to recreate
> the
> > cause by setting a short lease time then changing the IP address on every
> > renew. Any suggestions?
> >
>
>
> Can you explain in more detail exactly what's happening here. The renew
> starts with a client asking to renew an address. The server will either
> acknowledge that or send a DHCPNAK if the address isn't available. Are
> you saying that the server is sending a DHCPACK, but for a different
> address?
>
>
>
> Cheers,
>
> Simon.
>
>
I haven't looked at the packets because we don't have any way to recreate
the problem and we only have logs from our device. What we're seeing is
after the lease time (24 hours) expires our device gets a different IP
address, one more than the one it was using previously. I've checked
dnsmasq.leases and the MAC address only appears once so no idea how this
could be happening.

For the "renew every minute" problem our device is seeing the lease time
correctly but seems to be being sent the same IP address every minute.
We're running embedded Linux and using a recent version of udhcpc from
Busybox and we haven't seen any problems when running on other networks.

I'm pretty sure these problems are on the device running dnsmasq (I'm not
going to use the phrase "dodgy Chinese HW manufacturer"), I just wanted to
check whether there were any known problems in this old version of dnsmasq.
We'll probably get them to upgrade it anyway but I think this may be the
stability of their device in general - these aren't the only problems we're
seeing.

Tom
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