Mailing List Message #6043
From: Eric Berdahl <>
Subject: Re: SIMS and AirPort NAT
Date: Mon, 22 May 2000 13:54:27 -0700
To: SIMS Discussions <>
X-Mailer: CTM PowerMail 3.0.1 <>
Jeff Folk <mailto:> wrote:

>Let me see if I understand your situation. You have an AirPort base with an
>external [public] IP which port maps to SIMS on a separate machine at a
>internal [private] IP.


>Everthing in the IP range 10.0.1.xx should be able to
>connect to the SIMS server at its 10.0.1.xx IP number.


>But when you try to
>connect with the external [public] IP from within the local 10.0.1.xx
>subnet, you can't connect.


>From outside the 10.0.1.xx subnet you can connect
>to the SIMS servers using the external [public] IP or the 10.0.1.xx IP.

Incorrect. From outside the 10.0.1.xx subnet, I can connect to the SIMS
servers using the external [public] IP only.

>If this is correct then the issue is probably local NAT.

Very possible.

>IPNetRouter has two
>flavors of NAT. The external [subnet clients accessing external networks or
>external clients accessing internal portmapped subnet resources] is always
>on. Internal [subnet clients accessing local resources via external number
>or name] or local NAT is normally off. Local NAT is the translation where
>the router will remember the return path to the requesting client.

This sounds like a good candidate. I can see SIMS responding to the http
request, but the reponse never gets back to my PowerBook. If the AirPort
is failing to do the reverse mapping, that would explain my observations.
The question is, how does one fix this?

>may not even have this option, but if it does, turn it on.

I have been all over the AirPort configuration settings and do not see
anything about internal or local NAT. Hmmm...


Eric Berdahl                "We're sorry. We're morons. We're dumber
Man Behind the Curtain       than squirrels. We hear voices and do
Intelligent Paradigm         what they command. I have broccoli in my      socks."     - Pointy-haired Manager, "Dilbert"
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