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To: Russell Vincent <rv@groa.uct.ac.za>
cc: freebsd-questions@FreeBSD.ORG
Subject: Re: Problem with packet alias/natd 
In-reply-to: Your message of "Sat, 31 Aug 1997 13:13:30 +0200."
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Date: Sun, 31 Aug 1997 17:55:14 +0100
From: Brian Somers <brian@awfulhak.org>
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> I am seeing an anomoly when using natd to do address translation.
> 
> On a host (137.158.128.10):
> 
> # ipfw a 88 divert 8888 tcp from 137.158.128.1 to 137.158.128.10 23  
> 00089 divert 8888 tcp from 137.158.128.1 to 137.158.128.10 23
> # natd -v -p 8888 -a 137.158.128.10 redirect_address 137.158.128.7 0.0.0.0
> 
> I read that as anything received from host 137.158.128.1 to
> 137.158.128.10:23 is diverted to natd, which translates the source
> address to 137.158.128.10 (the aliasing machine) and destination
> address to 137.158.128.7.

Nope.  The source address should stay the same.  Natd will change the 
dst address to 137.158.128.7.

> The natd output after a telnet from 137.158.128.1 to 137.158.128.10:
> In  [TCP]  137.158.128.1:1096 -> 137.158.128.10:23 aliased to
>            137.158.128.1:1096 -> 137.158.128.10:23
> [ Repeated until I stop natd ]

Did you really leave out the ``-'' above (before redirect_address) ?  
I would suggest that this is the problem :-)

> Try a different tactic by picking up the alias address from the
> interface (de):
> 
> # natd -v -p 8888 -n de0 -redirect_address 137.158.128.7 0.0.0.0
> In  [TCP]  137.158.128.1:1100 -> 137.158.128.10:23 aliased to
>            137.158.128.1:1100 -> 137.158.128.7:23
> 
> Hmmm ... the interface address for de0 is the same as the '-a' address
> above (137.158.128.10).
> 
> i.e: Neither of the above works, but I get different results.
> 
> Am I doing something wrong or perhaps expecting too much
> from natd?

Hmm, I suspect the missing ``-'' is just a typo here.  The only thing 
I can see wrong with your setup is that you're not passing return 
traffic to natd:

  ipfw a 89 divert 8888 tcp from 137.158.128.10 23 to 137.158.128.1

Are you using the latest version of natd ?  Version 1.5 is on Ari's 
site (ftp.suutari.iki.fi) or on mine (www.awfulhak.org).  It's also 
in RELENG_2_2 & -current.

> Thanks
>  -Russell
> 

-- 
Brian <brian@awfulhak.org>, <brian@freebsd.org>
      <http://www.awfulhak.org>
Don't _EVER_ lose your sense of humour....