Hello,

I am about to put up a firewall machine to my friend, using of course
NetBSD. I, however, realized that my knowledge of (I figured: likely)
routing complications may not be quite up to the task. I do have an
idea that this is pretty simple case, but better be safe than sorry.


So here is the deal:

My friends local network is connected to 'net via ADSL. All machines will
have real IP addresses (which I don't know yet, so I'll use the 10
network as an example here).

The ADSL is at 10.0.0.1. The firewall has two NICs, addresses
10.0.0.2 and 10.0.0.3. The NIC at 10.0.0.2 is connected to ADSL
and NIC at 10.0.0.3 is connected to the LAN (whose addresses are
then 10.0.0.x, where x > 3).

What do I have to do to make traffic go both ways without trouble?

The LAN will need to have the firewall (10.0.0.2) as default gateway,
I suppose? And firewall's default gateway should then be 10.0.0.1,
right?

But right here I am on thin ice. Is all that enough, is the TCP/IP
stack smart enough to pass the traffic to correct interface or
what all do I have to set up. Routing tables... or what.


I have here at home my own firewall, and behind it two computers
that don't have real IPs so I use NAT, and all works nice... but
the above situation somehow felt like a very different world to me.

-- 
Arto Huusko  --  WWW: http://maailma.yok.utu.fi/
                  ** Divecalc **
The Diving Software @ http://maailma.yok.utu.fi/Divecalc