From: Cedric Blancher <blancher@cartel-securite.fr>
To: "Robert P. J. Day" <rpjday@mindspring.com>
Cc: netfilter mailing list <netfilter@lists.netfilter.org>
Subject: Re: are the four packet "states" all-encompassing?
Date: 24 Oct 2002 15:57:45 +0200 [thread overview]
Message-ID: <1035467865.16954.27.camel@elendil> (raw)
In-Reply-To: <Pine.LNX.4.44.0210240928360.32101-100000@localhost.localdomain>
Le jeu 24/10/2002 à 15:29, Robert P. J. Day a écrit :
> On 24 Oct 2002, Cedric Blancher wrote:
> > One very packet can have one state, and one.
> so every syntactically correct ("well-formed"??) packet is one
> of NEW, ESTABLISHED or RELATED, while all others are just
> INVALID? ok, i can accept that, thanks.
Yes and no, it is a bit more complicated...
INVALID applies to all packets for which ip_conntrack is not able to
give a state. As common examples :
. TCP packets that does not complies to RFC 793
. ICMP errors non related to existing flows
. lack of memory or conntrack table full
So, well formed packets can sometimes fall into INVALID state, but it is
safe to DROP them.
--
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:[~2002-10-24 13:57 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2002-10-24 11:37 are the four packet "states" all-encompassing? Robert P. J. Day
2002-10-24 11:58 ` Cedric Blancher
2002-10-24 13:29 ` Robert P. J. Day
2002-10-24 13:57 ` Cedric Blancher [this message]
2002-10-24 13:58 ` Robert P. J. Day
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