netdev - Re: [PATCH] Add IPv6 support to TCP SYN cookies

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Message-ID: <20080205215216.GB24275@2ka.mipt.ru>
Date:	Wed, 6 Feb 2008 00:52:17 +0300
From:	Evgeniy Polyakov <johnpol@....mipt.ru>
To:	Alan Cox <alan@...rguk.ukuu.org.uk>
Cc:	Andi Kleen <andi@...stfloor.org>,
	Glenn Griffin <ggriffin.kernel@...il.com>,
	netdev@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] Add IPv6 support to TCP SYN cookies

Hi Alan.

On Tue, Feb 05, 2008 at 09:20:17PM +0000, Alan Cox (alan@...rguk.ukuu.org.uk) wrote:
> > Most (if not all) distributions have them enabled and window growing
> > works just fine. Actually I do not see any reason why connection
> > establishment handshake should prevent any run-time operations at all,
> > even if it was setup during handshake.
> 
> Syncookies are only triggered if the system is under a load where it
> would begin to lose connections otherwise. So they merely turn a DoS into
> a working if slightly slower setup (and > 64K windows don't matter for
> most normal users, especially on mobile devices).

SACK is actually a good idea for mobile devices, so preventing
syncookies from not getting into account some options (btw, does it work
with timestamps and PAWS?) is not a solution.

-- 
	Evgeniy Polyakov
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