From: Changli Gao <xiaosuo@gmail.com>
To: Jan Engelhardt <jengelh@medozas.de>
Cc: Balaji Venkatamohan <bvenkat@ncsu.edu>, netfilter-devel@vger.kernel.org
Subject: Re: how to use regex inside new netfilter extension modules?
Date: Thu, 4 Mar 2010 09:33:04 +0800 [thread overview]
Message-ID: <412e6f7f1003031733n68bfa158v1b590a41c2ffa3d2@mail.gmail.com> (raw)
In-Reply-To: <alpine.LSU.2.01.1003031954001.25372@obet.zrqbmnf.qr>
On Thu, Mar 4, 2010 at 2:56 AM, Jan Engelhardt <jengelh@medozas.de> wrote:
> On Wednesday 2010-03-03 19:41, Balaji Venkatamohan wrote:
>>
>>I need to use regular expressions inside the point of decision match
>>function. I could not use 'regex.h ' or any other standard C library
>>inside any of xt_*.c or xt_c*.h files. I could also see that none of the
>>netfilter match extensions have them. I would also like to know why is it
>>so?
Please refer to the source code of l7filter. http://l7-filter.sourceforge.net/
>
> Regular expressions are not the cheapest, both time and memory-wise:
> you have to keep in mind NF runs in irq context. Furthermore, since
> you only see single packets rather than the connection stream, regexes
> prove to be far less useful.
REs are useful and cheapest in some conditions.
--
Regards，
Changli Gao(xiaosuo@gmail.com)
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prev parent reply other threads:[~2010-03-04 1:33 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-03-03 18:41 how to use regex inside new netfilter extension modules? Balaji Venkatamohan
2010-03-03 18:56 ` Jan Engelhardt
2010-03-04 1:33 ` Changli Gao [this message]
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