From: Cedric Blancher <blancher@cartel-securite.fr>
To: Matthew Donofrio <mdonof2@pride.hofstra.edu>
Cc: netfilter@lists.netfilter.org
Subject: Re: How exactly does RELATED work in Connection Tracking?
Date: 23 Oct 2002 15:26:22 +0200 [thread overview]
Message-ID: <1035379582.8853.69.camel@elendil> (raw)
In-Reply-To: <000b01c27aac$d6b2a270$09c809c0@PENT4>
Le mer 23/10/2002 à 17:57, Matthew Donofrio a écrit :
> The tuple is just the source address and destination address for a
> particular packet, correct?
No, because your box can have multiple different flows with the same
destination. A tuple as src address, dst address, layer 4 protocol and
layer 4 datas, such as src and dst ports for TCP or UDP.
> So is it safe to say that the only fields that are compared for
> connection tracking are the source and destination addresses?
No it's not sufficient. you have to look at layer 4 datas.
> So, if a packet comes in and the source and destination addresses
> match an entry in the conntrack state table, then we can say that
> it is part of some ESTABLISHED connection.
It is established if its tuple (as defined below) matches an entry in
the conntrack table, i.e. if it is the same than the tuples associated
to entries.
Good reading for you are :
http://www.gnumonks.org/presentations/netfilter-knf2002/netfilter-knf2002.pdf
http://www.gnumonks.org/presentations/netfilter-internals-lt2002/netfilter-internals-lt2002.pdf
--
Cédric Blancher <blancher@cartel-securite.fr>
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
next prev parent reply other threads:[~2002-10-23 13:26 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2002-10-22 5:48 How exactly does RELATED work in Connection Tracking? Matthew Donofrio
2002-10-22 22:21 ` Cedric Blancher
2002-10-23 15:57 ` Matthew Donofrio
2002-10-23 13:26 ` Cedric Blancher [this message]
2002-10-24 10:06 ` Antony Stone
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