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Date:      Sun, 10 Jul 2005 13:06:43 +0100
From:      "Greg Hennessy" <Greg.Hennessy@nviz.net>
To:        <freebsd-pf@freebsd.org>
Subject:   RE: PF & BLOCK MP3 (AVI)
Message-ID:  <20050710120644.5388B11@gw2.local.net>
In-Reply-To: <42D102E0.000001.03838@ariel.yandex.ru>

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> > Indeed, many commercial firewall vendors offer content 
> inspection in their products because customers want to buy it.
> Unfortunately, I do not know similar let and commercial 
> realizations similar let under BSD, capable to filter content 
> on FIREWALLS.

That's because you havent looked hard enough. 

> On Linux in IPTABLES it is remarkable works, and I do not see 
> the global reasons why on BSD in PF it cannot be realized, 
> even in the form of a patch or something similar?!??!

It doesn't 'work' period, pattern matching on a packet by packet basis is a
complete waste of time unless the pattern matching algorithms do full
reassembly and are application aware. Which is exactly what Content
Inspection/Fixups in commercial firewall products do.  (some better than
others mind you)

> P.S. It is insulting, that I has answered a question only my 
> compatriot, and developers led by Daniel Hartmeier it have ignored: (.

That's because running Regex against each packet is a daft idea, a
performance killer and a self inflicted DOS attack waiting to happen. 

5 minutes googling provides far superior & scalable solutions which can
dynamically update PF tables to kill unauthorised traffic. 

Such as. 

http://www.snortsam.net/index.html




Greg



 





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