DHCP response to source address not helper address

[Steven Carr]

On 26 June 2013 22:46, Jason Brandt <jbrandt at fsmail.bradley.edu> wrote:
> We are running a mixed environment of mostly public addresses, with some
> private (nat'd) addresses.  We are trying to use one pair of DHCP servers to
> service all networks.  The problem we've run into, is that instead of
> responding to source address, the DHCP server responds to the giaddr address
> in the DHCP packet.  Is there any way to force the server to respond to
> source address?  Here's an example of a request packet (1.98 is the
> translated source IP, 190.111 is DHCP server):

The problem is the DHCP server is on the "other" side of the NAT
gateway and the DHCP response is sent as a unicast packet to the
GIADDR. To get this to work you need a NAT gateway/firewall that has
the ability to modify/manipulate/translate the packets so that they
make sense on either side of the gateway (not sure which vendors have
this capability for DHCP) - or reside to the fact you need additional
DHCP server(s) on the un-NAT'd side.

Steve