DHCP through a router

[Brazen]

We are segmenting off a department in our company (for security reasons) with a linux firewall/router from the rest of our network. I really don't want to have to set up (and therefore manage) DHCP on this router. I would much rather those computers could still use our main DHCP servers.

Is there any way to have the linux router relay any DHCP requests on to our main DHCP servers?

 

[Brazen]

Ok, ok, I've found out that it IS possible, but I can't find how to actually do it? Could somebody maybe get me started setting it up through Webmin?

Wait, I just realized... DHCP will have to hand out a different subnet to the computers behind the router... any ideas on how I can solve this?

 

[spidey07]

you'll need a DHCP relay agent and just setup the scope with the correct IP address range on your DHCP server.

I'm sure you can do it with your linux box (relay agent), I just don't know the commands.

You essentially just tell the relay agent - "send DHCP request to this DHCP server"

 

[spyordie007]

Ok, ok, I've found out that it IS possible, but I can't find how to actually do it?

See spidey07's post above

Wait, I just realized... DHCP will have to hand out a different subnet to the computers behind the router... any ideas on how I can solve this?

You would setup multiple scopes for the various subnets, a little bit of information here:
http://tcpmag.com/careers/article.asp?EditorialsID=285
http://insight.zdnet.co.uk/hardware/servers/0,39020445,2110398-2,00.htm

 

[nweaver]

on cisco router's this is the "ip-helper" stuff. Your DHCP server looks at what subnet the original request comes from and then assigns it an address from the correct pool .We use one DHCP server for many subnets

 

[Pheran]

Spidey is correct, you need a DHCP relay agent on the Linux box. The ISC DHCP package provides this; the executable is called dhcrelay. If you have the dhcp package (RPM or whatever your distro uses) installed, try 'man dhcrelay'.

 

[Brazen]

Ok, thanks a bunch. Every one of you provided valuable information to get me started. I can usually figure out the details. I'll probably start on this at the end of next week. I have to re-configure about 30 printers with static IP addresses before then. yuck.

 

[Bluestealth]

Or a bridging firewall, but thats a little harder to segment.
DHCP Relay is the way to go for you.