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Date:      Sat, 2 Sep 2000 23:47:29 -0700
From:      Dragos Ruiu <dr@kyx.net>
To:        Bill Fumerola <billf@chimesnet.com>
Cc:        Nicolas <list@rachinsky.de>, freebsd-security@FreeBSD.ORG
Subject:   Re: ipfw and fragments
Message-ID:  <0009022351571F.20066@smp.kyx.net>
In-Reply-To: <20000903023759.O33771@jade.chc-chimes.com>
References:  <007a01c01457$3b9eff80$e4aa603e@gottt> <00090217534118.20066@smp.kyx.net> <20000903023759.O33771@jade.chc-chimes.com>

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On Sat, 02 Sep 2000, Bill Fumerola wrote:
> On Sat, Sep 02, 2000 at 05:50:02PM -0700, Dragos Ruiu wrote:
> 
> > > > Is there a way to make ipfw to reassemble fragmented ip packets before passing them through the rules?
> > > 
> > > No. The relevant bits are only in the first packet.
> > > 
> > It could be made to reassemble them, 
> > but it would incurr a performance hit.  
> 
> What do you gain? Nothing that I can think that ipfw currently
> tests for is in the non-initial fragment.
>

Correct me if I'm wrong because I havent looked at the ipfw source,
but fragment's dont get passed.  There are some applications that
like to send big packets (I have a video streaming system for instance
that sends up to 64K UDP datagrams) that will always get fragmented.
If I wanted to send such packets unmolested through ipfw it 
would have to "reassemble" them as it were so that once the first 
fragment got through the subsequent ones could follow too.

Or am I missing something here in what you're trying to do?

cheers,
--dr
-- 
dursec.com ltd. / kyx.net - we're from the future
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