Need some help with multi-netting/IP aliasing

Here is what I am trying to do.. The router that I have has two
ethernet interfaces and I want to give out private dynamic addresses to
some machines on a network and also be able to assign static public
addresses, either through DHCP reservation or physically assigned, to
other machines over the same wire from a single ethernet interface and
have both able to reach the internet and each other.

So the network would look somthing like this:

Public class C
address space
from upstream
|
My linux router
|
66.119.25.0/24 and 10.0.0.0/16
on the same wire going to the router

Is there a way to do this using multi-netting or is there a better way
of doing this?
Could someone point me in the right direction?

Christopher Tyler
Total Wireless Communications

(E-Mail Removed) wrote:
> Here is what I am trying to do.. The router that I have has two
> ethernet interfaces and I want to give out private dynamic addresses to
> some machines on a network and also be able to assign static public
> addresses, either through DHCP reservation or physically assigned, to
> other machines over the same wire from a single ethernet interface and
> have both able to reach the internet and each other.
>
> So the network would look somthing like this:
>
> Public class C
> address space
> from upstream
> |
> My linux router
> |
> 66.119.25.0/24 and 10.0.0.0/16
> on the same wire going to the router

I am assuming (?) that the Linux router is connected to a switch on the
LAN side.

> Is there a way to do this using multi-netting or is there a better way
> of doing this?
> Could someone point me in the right direction?

It is possible to run two distinct logical networks on the "same wire"
-- ie., same physical segment. But it requires a pretty good
understanding of Linux networking to avoid problems. Especially of
concern is that you would be mixing a "public" net and a "private" net
on the same wire which will complicate security measures that should be
in place.

Personally, I would go for a vlan capable switch connected to the LAN
side of Linux router. Linux router will provide upstream and
inter-vlan routing and the vlans will help make security easier to
manage. Linksys home routers running Linux can do this and do it very
well with 3rd party firmware. Here is a good start:

http://www.linksysinfo.org/

If you go the other route you could start with these for some
background:
http://linux-ip.net/html/ << good general networking background
http://lartc.org/howto/ << the "standard" advanced routing reference

http://www.policyrouting.org/PolicyR...NLINE/TOC.html
This is the one that goes into details and examples of running two
logical networks. Well, more accurate to say that the topic comes up,
but enough info is provided to get you well on the way to using policy
routing. Not for the faint hearted ;-)

good luck,
prg