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Date:      Tue, 27 Nov 2001 16:04:04 -0500 (EST)
From:      Chris BeHanna <behanna@zbzoom.net>
To:        <freebsd-security@freebsd.org>
Subject:   Re: Best security topology for FreeBSD
Message-ID:  <20011127160049.N57709-100000@topperwein.dyndns.org>
In-Reply-To: <20011127054030.GB5828@shall.anarcat.dyndns.org>

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On Tue, 27 Nov 2001, The Anarcat wrote:

> The firewall wether it is single or dual, have the same functionality,
> in the presence of a DMZ:
>
> (2 designs of dual fw):         (and a single fw design):
>
>   out    out                             out
>    |      |                               |
>   fw1    fw1----+                         |
>    |      |     |                         |
>   dmz     |    dmz                       fw ---- dmz
>    |      |     |                         |
>   fw2    fw2----+                         |
>    |      |                               |
>   in     in                              in
>
> In the second one, you setup a private line between the 2 fws to have
> direct traffic let through unsniffable directly by the dmz. That is,
                             ^^^^^^^^^^^
> even if you let direct traffic, where you might prefer having proxies
> somewhere to avoid direct traffic.

    No, not unsniffable.  If an attacker manages to install arp-spoof
software on the DMZ, then he can easily mount a man-in-the-middle
attack and reroute all the traffic between fw1 and fw2 through the
DMZ.  Even routers can be overcome.  There's a good discussion about
this kind of thing on the dsniff website.

-- 
Chris BeHanna
Software Engineer                   (Remove "bogus" before responding.)
behanna@bogus.zbzoom.net
I was raised by a pack of wild corn dogs.


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