netdev - Re: [PATCH 3/5] netfilter: xt_TCPMSS: Fix violation of RFC879 in absence of MSS option

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Message-ID: <20130610071954.GA13500@gmail.com>
Date:	Mon, 10 Jun 2013 03:19:54 -0400
From:	Phil Oester <kernel@...uxace.com>
To:	David Laight <David.Laight@...LAB.COM>
Cc:	Pablo Neira Ayuso <pablo@...filter.org>,
	netfilter-devel@...r.kernel.org, davem@...emloft.net,
	netdev@...r.kernel.org
Subject: Re: [PATCH 3/5] netfilter: xt_TCPMSS: Fix violation of RFC879 in
 absence of MSS option

On Tue, Jun 11, 2013 at 09:43:07AM +0100, David Laight wrote:
> Is setting the mss to 536 actually ever sensible?
> RFC 879 might say that it is the default (and the minimum
> that must be supported), but in practise the actual mss
> is very likely to be only slightly shorter than the standard
> ethernet mss.
> Although strict conformance with RFC 879 might require the mss
> be clamped to 536, pragmatically a value much nearer 1400 would
> make sense - systems with very low mtu/mss are probably likely
> to advertise it.

Read the associated bugzilla - there was at least one real world
example where setting a higher MSS was causing breakage.

Phil

https://bugzilla.netfilter.org/show_bug.cgi?id=662
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