Using two DHCP daemons in the same subnet, ignore a specific client

[Thomas Lange]

If you have two DHCP daemons in the subnet of your FAI infrastructure,
and one uses the option allow unknown-clients you are in trouble,
because if this daemon responses faster it will give the install
client an IP address and the other daemon has no chance to control the
clients boot parameters for FAI.

Now I've found a solution for this.

I have a DHCP daemon A which includes the allow unknown-clients
option. In the same subnet I like to run a second DHCP daemon B for my
FAI infrastructure which includes deny unknown-clients and contains a
list of all my install clients using their MAC address.

Since I know the MAC addresses of my install clients (that should be
controlled by B), I can tell DHCP A to ignore those clients.

For each install client I add a line into DHCPd.conf (of DHCP A) like this:

host demohost {hardware ethernet 00:14:0b:06:6e:4a;ignore booting;}

That's it. If demohost does a PXE boot, DHCP A will ignore it, and
DHCP B can answer the request.

-- 
regards Thomas