[tcpm] TCP option encoding in Timestamps

Pekka Savola <pekkas@netcore.fi> Tue, 19 February 2008 12:57 UTC

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Date: Tue, 19 Feb 2008 14:57:31 +0200 (EET)
From: Pekka Savola <pekkas@netcore.fi>
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Subject: [tcpm] TCP option encoding in Timestamps
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FYI,

This may be of interest;

RFC 4987 describes in Section 3.6 a FreeBSD 7.0 approach to encode TCP 
options in the TCP timestamp field in order to support a select set of 
TCP options when SYN cookies is enabled.

There's now a proposed Linux implementation as well.

This may be something worth thinking about in the context of 
draft-ietf-tcpm-1323bis as well.

---------- Forwarded message ----------
Date: Mon, 18 Feb 2008 15:45:12 -0800
From: Glenn Griffin <ggriffin.kernel@gmail.com>
To: ggriffin.kernel@gmail.com
Cc: dada1@cosmosbay.com, johnpol@2ka.mipt.ru, alan@lxorguk.ukuu.org.uk,
     andi@firstfloor.org, netdev@vger.kernel.org, linux-kernel@vger.kernel.org,
     yoshfuji@linux-ipv6.org
Subject: Re: [PATCH] Add IPv6 support to TCP SYN cookies

I've posted a series of patches that I believe address Andi's concerns
about syncookies not supporting valuable tcp options (primarily SACK,
and window scaling).  The premise being if the client support tcp
timestamps we can encode the additional tcp options in the initial
timestamp we send back to the client, and they will be echo'd back to us
in the ack.  Anyone interested have a look, and provide any suggestions
you may have.  The new patches are a superset of this patch, so if they
are accepted this is one obsolete.

Support arbitrary initial TCP timestamps
http://lkml.org/lkml/2008/2/15/244

Enable the use of TCP options with syncookies
http://lkml.org/lkml/2008/2/15/245

Add IPv6 Support to TCP SYN cookies
http://lkml.org/lkml/2008/2/15/246

--Glenn
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