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Date:      Fri, 09 Apr 1999 15:21:16 +0400 (MSD)
From:      "Sergey S. Kosyakov" <ks@Chg.RU>
To:        Darren Henderson <darren@jasper.somtel.com>
Cc:        security@FreeBSD.ORG
Subject:   RE: ipfw question regarding RFC1918 addresses
Message-ID:  <XFMail.990409152116.ks@chg.ru>
In-Reply-To: <Pine.BSF.4.10.9904082336450.18705-100000@jasper.somtel.com>

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Where is the place for divert rules? Check carefully, what do you want to do?
And one more - the better rules will be:

add deny all from 192.168.0.0/16 to any in recv ppp0
...
other deny rules
...
add divert _port_ ip from any to any via _external_if_0_
add allow ip from any to any

And start natd with "-u" flag.

Sergey.

On 09-Apr-99 Darren Henderson wrote:
> 
> Running ipfw and natd. I use the class A RFC1918 address for the internal
> network.
> 
> The way things are set up ipfw first sends everything to divert, allows
> all localhost stuff then disallows the RFC1918 stuff with
> 
> add deny all from 192.168.0.0:255.255.0.0 to any via ppp0
> add deny all from any to 192.168.0.0:255.255.0.0 via ppp0
> add deny all from 172.16.0.0:255.240.0.0 to any via ppp0
> add deny log all from any to 172.16.0.0:255.240.0.0 via ppp0
> add deny all from 10.0.0.0:255.0.0.0 to any via ppp0
>#add deny all from any to 10.0.0.0:255.0.0.0 via ppp0
> 
> (There are a handful of additional rules). Notice that last line is
> commented out. If I include that natd appears to stop working. I'm
> guessing that divert is converting an incomming packet to 10.0.0.x and its
> then passing through my ruleset with its new address and being disallowed.
> The simple solution would seem to be to move the RFC1918 stuff above the
> divert rule... is that the best solution however? Have I even come close?
> 
> The goal being to block 10.0.0.0/8 comming into the machine...
> 
> 
> ______________________________________________________________________
> Darren Henderson                              darren@jasper.somtel.com
> 
>                    Help fight junk e-mail, visit http://www.cauce.org/
> 
> 
> 
> To Unsubscribe: send mail to majordomo@FreeBSD.org
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---
----------------------------------
Sergey Kosyakov
Laboratory of Distributed Computing
Department of High-Performance Computing and Applied Network Research
Landau Institute for Theoretical Physics
E-Mail: ks@chg.ru
Date: 09-Apr-99
Time: 15:14:50
----------------------------------
---


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