dhcp config - 2 subnets on one phys net

Igor Antokhin igor at sai.msu.ru
Fri Sep 29 04:12:54 UTC 2006

Sorry for a question from a newbie, but I could not find a clear answer to 
mu problem - only pieces of the puzzle...

I have a computer on a physical network It runs Linux 
Fedora Core 5. It is just a client machine not providing any general 
use services like dns printing etc. Now for some reasons I want to create 
a private network for my department using the same physical ethernet.
I understand that what I have to do is this:

1.Install a dhcp server (done).

2.Create its config describing two subnets - one in which my 
dhcp server will NOT provide any address range (I simply do not have the 
authority to do that); and the other one e.g., with the range 
for dhcp clients say from to Define both 
subnets within a shared_network evironment. Done.

3.Accociate my private network with an alias of my network card eth0. 
e.g. eth0:1. Done.

4.On dhcp clients, use the address of my computer in that private 
network, e.g. as the gateway. (actually this should be done 

5.Assign my computer the ip for the interface eth0:1. Done.

6.Set up my computer as a router for the internal private network (serviced by eth0:1) - that is, enable forwarding of the 
packets between the two networks.

6.Set up NAT to properly masquerade packets from the private network.

Now, I don't know how to do the steps 5 and 6. Also, I am not sure if I 
did not miss something important in the general layout. Please advice!

Thanks for your help,

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