Subject: Re: IP/NAT questions
To: None <>
From: Tim McNamara <>
List: port-mac68k
Date: 02/16/2001 20:04:56
At 5:43 PM -0600 2/16/2001, Bob Nestor wrote:
>Tim McNamara wrote:
>>Well, I'm feeling slow on the uptake getting NAT set up.  It still
>>doesn't work.  My NetBSD box can connect to to the Internet via my
>>DSL router/hub without any problem.
>>Here's my configuration thus far (I *think* this is all of it):
>>defaultroute=""  (ISP's gateway)
>If you are still connecting your NetBSD system to your DSL router/hub
>rather than directly to your incoming DSL line then your default gateway
>is the router/hub.  As I recall that address in your configuration is

The router- a Flowpoint 2200- is stuck in bridge mode as configured 
by the ISP and is transparent , so as far as I know it has no 
identifiable IP address.  It has a built-in 4 port Ethernet hub and a 
line out for the line loop to the DSLAM.  There is also a "serial" 
port using an RJ45 e-net lack for accessing the router, which would 
be my only possibility for configuring the router directly.

All of my LAN addresses are 192.168.208.x using .1 for the iMac, .2 
for the NetBSD box and .3 for my PowerBook 145B when I get that 
working again.  I don't have any idea what if any internal IP address 
the router would have or if I need to specify it since it's 
functioning as a bridge rather than as a real router.

The DSL line comes into the house and into the DSL port on the 
router.  The NetBSD box and the  Mac OS box are both connected to one 
of the four ports in the built-in Ethernet hub on the router, since I 
only have one Ethernet port on either machine.  Under  Mac OS, Open 
Transport is manually configured to have an IP address of, using netmask and a gateway of which is the ISP's router connected to the DSLAM.  So 
I need to have the NetBSD box be the exposed host on the Internet 
using my static IP address, plus be the gateway to get packets off of 
and into the LAN.  Since I have one Ethernet port (at least 
currently, I could buy one if it would make this much easier) that 
means that sn0 has to do double duty with two IP addresses- one real 
one for the outside world and one internal one for the LAN.

>  >/etc/ifconfig.sn0
>>inet sugaree netmask
>I don't think this is correct.  It should be:
> netmask

I think that when I put that in (using being the 
address I was planning on for the NetBSD box within the LAN), the 
system could not access the Internet or have any connectivity within 
the LAN.  Getting this right could be the heart of the problem, 
though.  The configuration I am currently using in /etc/ifconfig.sn0 
is in accordance with the diagrams on Henry Hotz's site.

OK, so the external IP address (, static IP assigned by 
my ISP) is specified in /etc/hosts.  Does it NOT need to be specified 
in /etc/ifconfig.sn0?  /etc/ifconfig.sn0 should be used to specify 
the LAN-side IP address and not the external address?

>  >/etc/ifaliases  (this was mentioned in the NetBSD FAQs on networking)
>> sn0
>You only need this if you want to replace your DSL router/hub with the
>NetBSD box or if you want to configure your intranet (your side of the
>router/hub) such that your NetBSD box is supporting things like DNS,
>Netatalk, Samba, etc.

Ah, that's why no one mentioned it.  When I put it in, the LAN-side 
interface did appear in netstat -i whereas it hasn't with any other 
configuration thus far.  Didn't make any difference that I could see 
in terms of functioning.

>I'd sugget you start with trying to get just the NetBSD system working
>with minimal network setup/changes first.  Then add things to that one
>step at a time.  I've got a feeling you have two or three configurations
>in mind and you're trying to pick and choose options for each to merge
>into your setup.

I am trying to get the *simplest* setup that will allow both my iMac 
and my NetBSD box to access the Internet via my xDSL router.  For 
that reason I've avoided using dhcp, named etc.  The current setup 
does allow the NetBSD machine to access the Internet but does not yet 
do any actual NAT, and the iMac and NetBSD box can't talk to each 
other.  However, at this point I am just baffled and clearly lack 
enough knowledge to make this work.  I can certainly continue to use 
poor man's networking and just plug in whichever computer I want to 
use at a given time!

Thanks again for all the help.