Edubuntu does not work with DHCP Konfiguration on port 1067

Gavin McCullagh gmccullagh at
Mon Aug 7 17:26:53 BST 2006


On Mon, 07 Aug 2006, mailing-joergd at wrote:

> The classroom is already running a terminal server solution, which uses
> pxe. But it is a commercial solution, not very flexible. My task is to
> implement a thinclient solution WITHOUT touching the existing system. A
> testbed server is available, the clients will be booted via diskette.
> AFAIK, the best possibility to realize this is shifting edubuntu to work
> on dhcp port 1067.

Instinctively, running DHCP on two different ports with modified DHCP
clients sounds horrible but whatever works for you :-)

For what it's worth, I would be more inclined to shut down the DHCP on one
or other system and configure the other DHCP server to handle both systems.
That way you can use a standard PXE setup on clients and just reconfigure
the DHCP server to dictate which machines get Edubuntu and which get the
other system.  

Modified DHCP clients seems counter to the whole point of DHCP, but that's
just my instinct.

> I've done these steps: - Changed the dhcp server port in
> /etc/init.d/dhcp3-server - Configured a diskette via to
> work on port 1067/1068 (ALTERNATE_DHCP_PORTS_1067_1068)

The Edubuntu thin client system needs to be told to use port 1067. I guess
you  should be able to modify dhclient.conf to tell it to use a different
port but I can't find this option documented anywhere.  I do see in the
manpage of dhclient that it can be passed port options on the command line,
eg "-p 1068" so I'd imagine there should be a config file option.  

If it came to it, you could rebuild the dhcp3-client package and install it
into your edubuntu chroot with the default port number changed in the
source.  (ick!)  It looks like you need to look at client/dhclient.c line

> The client's first dhcp request is correctly answered, and he gets his
> linux image via tftp. So far so good...
> Unfortunately, there's trouble when the client sends his second dhcp
> request. He gets the wrong ip configuration, as he asks the wrong (the
> existing) dhcp server. Consequentially, the client is unable to mount the
> nfs.

That sounds about right.

> As far as I understood, the option-129 setting only works with etherboot
> images. Edubuntu does not deliver etherboot images by default. Therefore,
> I created a etherboot image as described at
> .

Sorry, I don't know enough about this stuff to be of much help.  However, I
guess the ultimate goal must be to convince dhclient to use the other port
so I'm unclear exactly how dhclient gets passed this info.  

> option option-129 "DPORT=1067";

Just a small thing.  If you want DHCP on 1067,1068, dhclient needs to be
passed the command line "-p 1068" (otherwise it uses 1066,1067).  I presume
that's not your problem (or you'd be getting no dhcp response).  Just a

Sorry I can't help more,

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