linux-kernel - Re: [PATCH] xt_TCPMSS: SYN packets are allowed to contain data

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Message-ID: <alpine.LSU.2.01.1001202238400.18680@obet.zrqbmnf.qr>
Date:	Wed, 20 Jan 2010 22:39:09 +0100 (CET)
From:	Jan Engelhardt <jengelh@...ozas.de>
To:	Simon Arlott <simon@...e.lp0.eu>
cc:	Patrick McHardy <kaber@...sh.net>,
	William Allen Simpson <william.allen.simpson@...il.com>,
	netdev <netdev@...r.kernel.org>,
	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
	netfilter-devel@...r.kernel.org
Subject: Re: [PATCH] xt_TCPMSS: SYN packets are allowed to contain data

On Wednesday 2010-01-20 22:21, Simon Arlott wrote:

>The TCPMSS target is dropping SYN packets where:
>  1) There is data, or
>  2) The data offset makes the TCP header larger than
>  the packet.
>
>Both of these result in an error level printk.
>
>This change fixes the drop of SYN packets with data
>(because the MSS option can safely be modified) and
>passes packets with no MSS option instead of adding
>one (which is not valid).

Can you explain why the automatic addition of a MSS option is removed?
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