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Date:      Sun, 15 Mar 2009 13:40:13 +0300
From:      Sergey Matveychuk <sem@FreeBSD.org>
To:        Luigi Rizzo <rizzo@iet.unipi.it>
Cc:        freebsd-ipfw@freebsd.org, Dmitriy Demidov <dima_bsd@inbox.lv>
Subject:   Re: keep-state rules inadequately handles big UDP packets	or	fragmented IP packets?
Message-ID:  <49BCDB0D.6070608@FreeBSD.org>
In-Reply-To: <20090315100206.GA63505@onelab2.iet.unipi.it>
References:  <200903132246.49159.dima_bsd@inbox.lv>	<49BBB94A.7040208@FreeBSD.org>	<200903142031.53326.dima_bsd@inbox.lv> <49BCCC9D.30109@FreeBSD.org> <20090315100206.GA63505@onelab2.iet.unipi.it>

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Luigi Rizzo wrote:
> On Sun, Mar 15, 2009 at 12:38:37PM +0300, Sergey Matveychuk wrote:
>> Dmitriy Demidov wrote:
>>> Hi Luigi. Thank you for answer.
>>> It is a big "surprise" for me that reassembling of IP datagrams is done 
>>> not *before* they go into firewall, but *after* :(
>> But what's wrong with it? A fragment got from net, pass firewall and 
>> store. After all fragments we got, OS reassembly a packet and pass it 
>> through firewall again.
> 
> Currently we don't have a way to re-invoke the firewall after
> reassembly. In fact, we should probably provide hooks before and
> after reassembly, and use them in a configurable way.

It sounds like a security issue. We can construct any packet that pass 
through firewall?

-- 
Dixi.
Sem.



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