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Date: Tue, 6 Jul 2004 13:05:49 -0700
From: Stephen Hemminger <shemminger@osdl.org>
To: Jamie Lokier <jamie@shareable.org>
Cc: netdev@oss.sgi.com, linux-net@vger.kernel.org,
       linux-kernel@vger.kernel.org
Subject: Re: [PATCH] fix tcp_default_win_scale.
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On Tue, 6 Jul 2004 20:40:34 +0100
Jamie Lokier <jamie@shareable.org> wrote:

> Stephen Hemminger wrote:
> > Recent TCP changes exposed the problem that there ar lots of really
> > broken firewalls that strip or alter TCP options.  When the options
> > are modified TCP gets busted now.  The problem is that when we
> > propose window scaling, we expect that the other side receives the
> > same initial SYN request that we sent.  If there is corrupting
> > firewalls that strip it then the window we send is not correctly
> > scaled; so the other side thinks there is not enough space to send.
> 
> If a firewall strips the window scaling option in both directions,
> then window scaling is disabled (RFC 1323 section 2.2).
> 
> Are you saying there are broken firewalls which strip TCP options in
> one direction only?

It appears so.