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From: Cedric Blancher <blancher@cartel-securite.fr>
To: Anders Fugmann <afu@fugmann.dhs.org>
Cc: "Jens Lechtenbörger" <lechten@wi.uni-muenster.de>,
	netfilter@lists.netfilter.org
Subject: Re: NEW vs INVALID
Date: 01 Oct 2002 10:49:14 +0200	[thread overview]
Message-ID: <1033462154.878.17.camel@elendil> (raw)
In-Reply-To: <3D98620B.2070707@fugmann.dhs.org>

Le lun 30/09/2002 à 16:39, Anders Fugmann a écrit :
> Anyhow, AFAIK, the INVALID target only matches  ackets which are 
> malformed. a SYN-FIN packets is not malformed as such. (But yes, SYN-FIN 
> is an illegal combination, and should be dropped, though this is not the 
> purpose of the INVALID match (IMHO, this can easily be done using 
> standard netfilter rules).

By the way, I was wondering why --syn was "only" equivalent to :
	--tcp-flags SYN,ACK,RST SYN

And not to :
	--tcp-flags SYN,ACK,RST,FIN SYN

I know it is definitly easy to filter according to such criterias, but I
was just wondering if there were a good reason why --syn should match
such packets (maybe should have asked netfilter-devel).

-- 
Cédric Blancher
Consultant en sécurité des systèmes et réseaux  - Cartel Sécurité
Tél: +33 (0)1 44 06 97 87 - Fax: +33 (0)1 44 06 97 99
PGP KeyID:157E98EE  FingerPrint:FA62226DA9E72FA8AECAA240008B480E157E98EE


  reply	other threads:[~2002-10-01  8:49 UTC|newest]

Thread overview: 8+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2002-09-30 10:18 NEW vs INVALID Jens Lechtenbörger
2002-09-30 14:39 ` Anders Fugmann
2002-10-01  8:49   ` Cedric Blancher [this message]
2002-10-01  9:05     ` Anders Fugmann
2002-10-01 11:19       ` Cedric Blancher
2002-09-30 15:26 ` Cedric Blancher
2002-09-30 15:50   ` Jens Lechtenbörger
2002-10-01 10:33     ` Martijn Klingens

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