[lug] Networking question: multiple IPs and NAT?

[David Anselmi]

You didn't say what modem, but my experience is only with Cisco 678s.

Chris wrote:
[...]
> He's got 5 IPs from his ISP, all going to a DSL modem.
[...]
> It looks like we want to do something like this:
> 
> http://www.shorewall.net/NAT.htm 
[...]
> Can this be done by a typical DSL modem?

The 678 does not do one-to-one NAT the way shorewall shows it.  But you 
can assign one public IP to eth0 and NAT that to machines on a private 
LAN, and assign the rest of the pubilc IPs to one of the vip interfaces 
and use them on the various computers you have.

I suspect this may mean running two subnets on the same LAN segment, 
which is prone to confusing people.

Here's a thread on it:

http://clue.denver.co.us/pipermail/clue-tech/2001-December/002315.html

and a doc with pictures here:

http://www.qwest.com/dsl/customerservice/downloads/docs/nat.pdf

And these two discuss configuration for a public netblock without NAT:

http://www.qwest.net/nav4/help/your_acct/set_cisco_675.html

http://www.mailarchive.ca/lists/comp.dcom.xdsl/2001-09/1270.html

Dave