IP Aliasing Question

I've got several machines with addresses on a class C network and several machines on a subnet of a another class C network (29 bit netmask, 6 useful addresses).  

The subnetted machines have addresses that were assigned by my ISP.  I'd like to run all machines on the same ethernet with a Linux box having one address in each address space in order to route packets between the two.

I am running Redhat 4.1.

Will IP aliasing do what I need?

The two networks are 198.183.251.000/24 and 205.253.105.80/29.

Can two networks exist on the same wire with different netmasks?

Will I need to compile a new kernel?

What else would I need to do to achieve the desired effect.
Robbins012597Asked:
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knowledge021097Commented:
You can do what you want (although it is more normal to insert two cards in the Linux box and use separate physical networks). You need IP forwarding and IP aliasing on in the kernel.

Set up the Linux box as if it were only on one network, and get that working (let's say 198.183.251.1).  There's nothing special you need to do to run two  independent networks on the same wire.

Now, read the IP alias mini-HOWTO (www.ecsnet.com).  Basically, you use ifconfig on eth0:0 to set up the alias, eg:
      ifconfig eth0:0 205.253.105.81 netmask 205.253.102.248
Then add a route so it knows to send packets to the right network:
      route add -net <see "man route">

Test that you can ping machines on both networks, then make sure
every OTHER machine has the linux box as a default route (or just for the other network, if your situation is more complex).
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