dhcp and netfilter

[Nico Leidecker <nleideck@ix.urz.uni-heidelberg.de>]

Hi there,

I ran into trouble with dhcp and netfilter:
A simple kernel (2.6) module (on a machine, that also runs a dhcp
daemon) detects every new dynamic configured hosts in the network.
That should be achieved by simply hooking into the netfilter (outgoing)
chain and waiting for the DHCPACK to get some informations such as ip
and mac address from that packet.
So far, I thought, no problem. But the DHCPACK does not seem to go
through the netfilter. (And I read some posts, that a DHCP conversation
actually does not go through it at all. And that may be due to the use
of raw sockets...).
Though, my module can log DHCPOFFER but not the -ACK.

My Question:
Why is only DHCPACK not captured by my module, and how could I force a
dhcp-server's traffic to be filtered? Is that even possible?

I was using the dhcp3-server debian package.

best regards :)

Nico