On 23/10/2012 12:05, Christoph Pleger wrote:
> Hello,
>
> I am running a DHCP-Server that serves multiple subnets. The server has
> an IP address in all of these subnets, and its primary IP address in a
> subnet that is not served by DHCP. Every IP address has its own VLAN
> Ethernet interface, eth0.102, eth0.104, etc. In this setup, the DHCP
> server often does not send its unicast replies on the interface where it
> received the corresponding request, but on the interface of its primary
> IP address, and with that IP. My first thought how to change this was by
> setting routes depending on destination addresses, but this would cause
> big problems with other services running on the same machine, so I tried
> to combine iproute2 and iptables, like this:
>
If there any particular reason why you have the DHCP server on the same 
subnet as your DHCP clients?

I know I'm not answering your questions, but I wouldn't set it up that 
way in the first place on my own environments.

-- 
Regards,

Giles Coochey, CCNA, CCNAS
NetSecSpec Ltd
+44 (0) 7983 877438
http://www.coochey.net
http://www.netsecspec.co.uk
giles@coochey.net