[Dnsmasq-discuss] Restrict DHCP providing default gateway to *one* host on one network

[Will Dennis (Live.com)]

OK, this works - thanks TJ & Simon!

So as I understand it, the line:
dhcp-option=tag:vl20-ovsbr0,tag:wanem-20,3
means: for the machines tagged "vl20-ovsbr0" (which includes the WANem
machine's 2nd NIC), just use whatever the default option would be for the
router; but on machines tagged "wanem-20" (which matches ONLY the WANem
machine's 2nd NIC), set a NULL router option.
Correct? And, does order of application matter, or how else does dnsmasq
resolve the two options that match for the WANem VM's 2nd NIC?

Thanks again to everyone for their help in this!

Best,
Will

-----Original Message-----
From: dnsmasq-discuss-bounces at lists.thekelleys.org.uk
[mailto:dnsmasq-discuss-bounces at lists.thekelleys.org.uk] On Behalf Of Simon
Kelley
Sent: Wednesday, April 24, 2013 5:01 AM
To: dnsmasq-discuss at lists.thekelleys.org.uk
Subject: Re: [Dnsmasq-discuss] Restrict DHCP providing default gateway to
*one* host on one network

On 24/04/13 08:58, TJ wrote:
> On 23/04/13 15:33, Will Dennis (Live.com) wrote:
>> interface=vl10-ovsbr0
>> interface=vl20-ovsbr0
>> bind-interfaces
>> dhcp-range=vl10-ovsbr0,192.168.10.50,192.168.10.150,4h
>> dhcp-range=vl20-ovsbr0,192.168.20.50,192.168.20.150,4h
>> dhcp-host=52:54:00:d5:ee:4d,id:*,192.168.10.1
>> dhcp-mac=set:wanem-20,52:54:00:45:8c:6a
>> dhcp-option=vl10-ovsbr0,3,192.168.10.254
>> dhcp-option=tag:vl20-ovsbr0,tag:!wanem-20,3,192.168.20.254
>> log-dhcp
>
> I may be mis-reading the manual but as I understood it dnsmasq will 
> issue a default set of options for each range.
>
> dhcp-range=vl20-ovsbr0 will get a default option 3 which will be the 
> IP of the host running dnsmasq
>
> dhcp-mac=set:wanem-20 sets a tag for the exceptional client
>
> dhcp-option=tag:vl20-ovsbr0,tag:!wanem-20 will set a (possibly different)
gateway for non-exceptional clients.
>
> At this point the exceptional client will have the default option 3 for
the range. I think what you need is to not send any default route at all
when the exceptional client makes a request:
>
> dhcp-option=tag:vl20-ovsbr0,tag:wanem-20,3

I concur. Will, you've just omitted the empty option 3 from the last
dhcp-option.

(Wanders off to teach dnsmasq to complain in this situation.......)


Cheers,

Simon.

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