[SunHELP] 1 NIC router/firewall?

[Chad A. Chance]

Is this possible?

Here is the situation:
I'm going to be switching circuits, I currently have a P200 Linux box acting
as my router/firewall, I am bringing in a circuit to replace the current
one. I need to keep the old circuit active while I switch all the users over
to the new circuit. Problem is, I don't have enough hardware to make a new
router/firewall and keep the old one active.

Here is my proposed solution(if this will work)
Use this extra SS20 I have as a temporary router/firewall with only the
onboard ethernet, then replace it with the P200 after all the users are
switched over.

The question is, can I have 2 IPs on the single ethernet port of the SS20,
one public, one private, and plug it into the switch with the new circuit
and have it route between the 2 IPs? Will my user PCs be safe on their
10.1.X.X network even though they are plugged into a switch that directly
connects to the internet?

This seems like it would work, does anybody have an experiance with such a
setup?

TIA,
Chad