Problems with DHCP using VLANs

Tim Gavin livewire98801 at
Thu Aug 27 18:48:39 UTC 2009

The INTERFACES= statement was in the sample dhcpd.conf file that was
included with my dhcp3-server package, but it appears that it's not
being observed.  I've removed it from my config.  There were no
errors, it appears to just be ignored.

Without the /etc/default/dhcp3-server script in place, my server is
running beautifully, though I did get the 'no subnet declaration' for
the interfaces I'm not doing DHCP for.  IIRC, this is the 'normal'
behaviour, or at least it used to be.

Thanks for pointing that out, I imagine that if I had left that
statement in the config, some future upgrade would have broken, and
I'd be left with no idea why :)

Thanks again for all your help. . . I was finally able to retire my
last windows DHCP server.  woot :)


On Thu, Aug 27, 2009 at 10:56, Simon Hobson<dhcp1 at> wrote:
> Tim Gavin wrote:
>>  > Actually, /etc/default/dhcpd3-server does NOT override
>>>  /etc/dhcp3/dhcpd.conf. It provides command line options for the startup
>>>  script in /etc/init.d to pass to the server.
>>>  You either need a config file (and /etc/default is standard on Debian
>>> based
>>>  systems) or you end up hacking the startup scripts to set options.
>> The standard /etc/dhcp3/dhcpd.conf was there, as was
>> /etc/default/dhcpd3-server .  The 'default' script had an INTERFACES=
>> line, as did the dhcpd.conf, and the one in the 'default' script was
>> taking precedent somehow.  That was the only info in that script, so I
>> just deleted it and took out the reference to it in
>> /etc/init.d/dhcp3-server
> OK, it seems you didn't pick up on what I wrote. A list of interfaces is
> passed as command line arguments, NOT picked up from dhcpd.conf (where a
> line with "interfaces=" should have been flagged as an error). The two files
> serve DIFFERENT functions and both are needed.
> In /etc/init.d/dhcp3-server, the key bit is :
>>                start-stop-daemon --start --quiet --pidfile $DHCPDPID \
>>                        --exec /usr/sbin/dhcpd3 -- -q $INTERFACES
> here $INTERFACES is passed as command line arguments when dhcpd3 is started.
> Without /etc/default/dhcpd3-server (or another file to do the same job) then
> you would have to edit the script itself which could potentially cause
> problem when upgrading. Once you edit a script, an upgrade may mean choosing
> between throwing away your changes or keeping an old (and potentially
> sub-optimal) script.
> Obviously different people have different preferences, since I almost
> exclusively use Debian I find their way of doing things comes naturally to
> me.
> Had ISC decided to put the interface list in the main conf file then we
> wouldn't be having this discussion - I assume they had their reasons for
> that choice. Other command line arguments need to be separate - you can't
> specify the config file to use in the config file ! For most people, the
> compiled in defaults will do most of the time, if not all.
> --
> Simon Hobson
> Visit for books by acclaimed
> author Gladys Hobson. Novels - poetry - short stories - ideal as
> Christmas stocking fillers. Some available as e-books.
> _______________________________________________
> dhcp-users mailing list
> dhcp-users at

More information about the dhcp-users mailing list