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Date:      Thu, 21 Nov 2002 09:39:18 -0600
From:      David Kelly <dkelly@hiwaay.net>
To:        "Patrick M. Hausen" <hausen@punkt.de>
Cc:        Helge Oldach <freebsd-stable-21nov02@oldach.net>, archie@dellroad.org, guido@gvr.org, sullrich@CRE8.COM, greg.panula@dolaninformation.com, FreeBSD-stable@FreeBSD.ORG
Subject:   Re: IPsec/gif VPN tunnel packets on wrong NIC in ipfw? SOLUTION AND QUESTIONS
Message-ID:  <20021121153918.GA58136@grumpy.dyndns.org>
In-Reply-To: <200211211504.gALF4Sej086710@hugo10.ka.punkt.de>
References:  <20021121145332.GA57883@grumpy.dyndns.org> <200211211504.gALF4Sej086710@hugo10.ka.punkt.de>

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On Thu, Nov 21, 2002 at 04:04:28PM +0100, Patrick M. Hausen wrote:
> 
> > Other than my decrypted packets have started appearing to ipfw as if
> > they were coming from fxp1 (which is what started this mess) everything
> > else is working just fine.
> 
> It is only filtering the decrypted packets that I'm talking about
> all the time. It's impossible to build a filter that says:
> 
> - ESP from my peer is OK
> - 10... to 192.168... is OK if it's coming out of the ESP tunnel
> - 10... to 192.168... is _not_ OK if it's coming in my external IF
>   in plain text
> 
> If you want to allow the derypted traffic in, you have to allow all
> traffic with identical addresses, even if it hasn't arrived
> through the ESP tunnel but just came to the outside IF of your
> network by some other route. 

I understand now. 

I can say ESP to/from my peer is OK.

I can't (with ipfw) say my private addresses are OK if via ESP, have to
trust that setkeys and the kernel IPsec stuff isn't allowing anything
but.

Until decrypted packets started appearing to ipfw as if they came from
the IF they tunneled in via ESP, I could protect my external IF.

An esp0 or ipsec0 device would provide the handle ipfw needs.

-- 
David Kelly N4HHE, dkelly@hiwaay.net
=====================================================================
The human mind ordinarily operates at only ten percent of its
capacity -- the rest is overhead for the operating system.

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