DHCP IP Helpers

[addressesme]

Hi,

I'm new to Linux and am having some problems with the following lab environment.

I have downloaded Centos7 Minimal ISO and have installed this in a VM. I have then configured 4 network interfaces as follows;
- 10.0.10.1
- 10.0.20.1
- 192.168.0.1
- 172.16.0.1

This server is acting as my router. All interfaces are configured to route traffic between different subnets.

I have two domain controllers (Windows Server 2012 R2) - one on the 10.0.10.0 network and also one on the 10.0.20.0 network. These are acting as DHCP servers.

I have clients on the 192 and 172 networks and would like these to receive DHCP addresses from the DHCP servers on the 10 networks.

Now, DHCP broadcasts will not forward beyond their home subnets unless I configure an IP helper on the router and it is this I am really struggling with.

First question - can I do this with Cenos 7 minimal? I ask because a lot of the packages I presume are not installed by default.

I have been trying to use the 'ip helper-address a.b.c.d' command, but this doesn't appear to be installed - again is this due to the ISO I have installed and can I / how do I get this installed?

Thanks in advance,

M

[aks]

IP helpers - aka dhcp relay is usually done one the router(s).
I note you have two DHCP servers - I hope they are on seperate networks (by default 10.0.0.0/8 is a class A).

[addressesme]

IP helpers - aka dhcp relay is usually done one the router(s).
I note you have two DHCP servers - I hope they are on seperate networks (by default 10.0.0.0/8 is a class A).

Hi Aks,

Yes, they are on separate networks.

Ignoring the fact I have two DHCP servers for one second, DHCP Server A is on a class A network but has scopes configured to distribute addresses within other class B or C networks.

The question was how do I configure CentOS to relay these packets?

Thanks,
M

[stephenw]

Hello

DHCP Relay agent can be configured to listen on the interface in the subnet that has no DHCP server. It will then "relay" DHCP requests to the address of a DHCP server.

See Networking Guide: DHCP Relay Agent


HTH