[Dnsmasq-discuss] illegal domain in dhcp-config directive

[Simon Kelley]

Jason Dixon wrote:
> Thanks to the recent vulnerability, I'm upgrading an older dnsmasq
> system from version 2.34 to 2.45.  I've installed it and attempted to
> run it, but I get the following error.
> 
> dnsmasq: illegal domain 04-06.lab.foobar.com in dhcp-config directive.
> 
> The same configuration works fine with 2.34, so I presume something has
> changed in the configuration syntax or default settings.  I haven't
> found anything on Google or in the FAQ about this error, nor do I see
> any "dhcp-config" directives in our config files or the sample config.
> Here is the relevant line from our config:
> 
> dhcp-host=00:0c:29:02:1f:06,ubuntu-8.04-06.lab.foobar.com,172.16.117.105
> 
> It doesn't appear to be anything specifically with that line.  We have a
> couple hundred of these loaded by dnsmasq.  If I comment out that one,
> the next preceding one will error.  I'm not experienced with dnsmasq, so
> I'm putting myself at the mercy of this list.  Any help will be greatly
> appreciated.  :)
> 
> Thanks,
> 

As far as I can see, this error can only be occuring because the domain 
part of the name your applying to that host doesn't match the domain 
specified for dnsmasq to use by the domain=<domain> config option.

AFAIK dnsmasq has never allowed you to send a FQDN to a host unless it 
matches the domain setting (this is to avoid hosts impersonating, eg 
www.microsoft.com) but the check in this case has been moved from 
run-time, where it will log an error, to a fatal error at start-up

The fix may be as simple as adding

domain=04-06.lab.foobar.com

(and you can remove the domain parts from all the dhcp-host lines as 
well, if you wish. If they stay, they must match the domain given)

Cheers,

Simon.