How to configure a linux router to forward DHCP and TFTP for PXE boot

I am setting up pxe boot in a lab environment.  
One one side I have a commercial PXE server, on the other side in separate subnets I have the client machines.  The PXE server side is behind NAT/PAT.

In between I have a Linux 2.4 based router with iptables, conntrack etc. based off debian (Sarge if I recall correctly)  I have not figured out where to run DHCP from (I can do it at this router, or on the PXE server)

I can probably figure out the TFTP udp settings, but I'm not clear on what is the iptables equivalent of cisco's "IP helper".

My understanding of the problem for PXE, is simply DHCP and TFTP traffic need to make it to the PXE server/DHCP server.  
I can provide exact versions of kernel modules etc if needed.  
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akameswaranAsked:
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Michael WorshamConnect With a Mentor Infrastructure / Solutions ArchitectCommented:
What you are asking for is called DHCP Relay...

Pre-Boot Execution Environment (PXE) clients require an Internet Protocol (IP) address from a Dynamic Host Configuration Protocol (DHCP) server to begin the installation process from a Remote Installation Services (RIS) server. If the PXE client is located across a router from the DHCP server and/or the RIS server, the client may not receive an IP address from the DHCP server or configuration information from the RIS server.

DHCP clients located across a router from a DHCP server require that the router be configured to forward DHCP traffic to a DHCP server on a remote subnet. This traffic is broadcast traffic and routers do not normally forward broadcast traffic unless configured to do so.

Man Page: http://www.digipedia.pl/man/dhcrelay.8.html

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Also if you have two DHCP systems, I recommend this EE PAQ'd solution as well...

Can DHCP for PXE co-exist on the same network with another DHCP server?
http://www.experts-exchange.com/Networking/Protocols/DHCP/Q_24402692.html
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