Problems with DHCP using VLANs
Simon Hobson
dhcp1 at thehobsons.co.uk
Thu Aug 27 17:56:26 UTC 2009
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 http://www.magpiesnestpublishing.co.uk/ for books by acclaimed
author Gladys Hobson. Novels - poetry - short stories - ideal as
Christmas stocking fillers. Some available as e-books.
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