From: Ralf Spenneberg <lists@spenneberg.org>
To: Atsushi Nakagawa <atnak@chejz.com>
Cc: Netfilter <netfilter@lists.netfilter.org>
Subject: Re: Dropping RST of SYN
Date: 04 Sep 2003 11:13:20 +0200 [thread overview]
Message-ID: <1062666800.1615.23.camel@kermit> (raw)
In-Reply-To: <20030904183027.9CC5.ATNAK@chejz.com>
Am Don, 2003-09-04 um 10.50 schrieb Atsushi Nakagawa:
> What iptables table/rule can I use to drop RST (TCP) packets that're in
> reply to SYN?
> This is what I want it to do:
>
> -SYN-> [NEW] -SYN->
> [CLOSED] <-RST-
> ^
> IF TCP & [NEW]: DROP '<-RST-' & SET [CLOSED]
Using the current state implementation, AFAIK this is not possible.
The RST is already an established packet. There is no way to
differentiate between this RST and a later valid and needed RST packet.
You can only drop all RST packets
-m state --state ESTABLISHED -p tcp --tcp-flags RST,ACK RST,ACK -j DROP
Cheers,
Ralf
--
Ralf Spenneberg
RHCE, RHCX
Book: Intrusion Detection für Linux Server http://www.spenneberg.com
IPsec-Howto http://www.ipsec-howto.org
Honeynet Project Mirror: http://honeynet.spenneberg.org
next prev parent reply other threads:[~2003-09-04 9:13 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2003-09-04 8:50 Dropping RST of SYN Atsushi Nakagawa
2003-09-04 9:13 ` Ralf Spenneberg [this message]
2003-09-08 5:51 ` Dharmendra.T
2003-09-08 10:02 ` Chris Brenton
2003-09-08 10:58 ` Atsushi Nakagawa
2003-09-08 11:29 ` Chris Brenton
2003-09-08 11:53 ` Stephen Satchell
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