Ah, I see the source of confusion. All my macs are connected to a hub ... 
as is the cable modem. So, it looks like this:

                             -------------
	outside world <---> | Cable Modem |
                             -------------
                                   ^
                                   |
                                   v
                             -------------
                            |     Hub     |
                             -------------
                             ^     ^     ^
                             |     |     |
                   ----------      |      -------
                  |                |             |
                  v                v             v
              --------          --------     --------
             | Mac #1 |        | Mac #2 |   | Mac #3 |
             | NetBSD |        | MacOS  |   | MacOS  |
              --------          --------     --------

And I'd like the NetBSD machine to be the gateway. Currently, it's Mac #2 
running IPNetRouter.

I hope this makes sense.

	-- Mark

>Mark de Jong wrote:
>> Hi,
>>
>> I was reading the "How-TO regarding IP-NAT" by Armen Babikyan,
>> armenb@moof.ai.mit.edu and came to the following disturbing line:
>>
>> "if you have a cable modem you wish to route data over, be sure to have the
>> correct device number (cable modem and your lan will both be using
>> Ethernet, so you will need two Ethernet cards for your machine!) and
>> replace the device number (most likely either ae0 or ae1)."
>>
>> Do I really need two ethernet cards for this to work? My goal is to make my
>> MacIIcx my gateway machine for all the rest of my Macs on the net. Up until
>> now I have been running "IPNetRouter" under MacOS, and it works great ...
>> with one ethernet connection.
>>
>> Is there anyway to use IP-Nat on NetBSD without the need for two ethernet
>> cards?
>
>most cable modems connect to an ethernet card.  what does yours connect
>to?  if it connects to your ethernet card, what are the other machines on
>the network connected to? 
>
>in order for a machine to be a gateway, you usually have a setup like:
>
>                            ---------------------------
>                            |                         |
>	outside world <---->| interface1   interface2 | <------> LAN
>                            |                         |
>                            |      gateway machine    |
>                            ---------------------------
>
>in your case, interface1 would be the cable modem, and interface2 is
>probably an ethernet card.  is this not how your system is set up?
>
>later.
>
>colin


___________________________________________________________________________
Mark de Jong                Macintosh Development              mdj@home.com