Date: Tue, 5 Feb 2008 21:20:17 +0000
From: Alan Cox <alan@lxorguk.ukuu.org.uk>
To: Evgeniy Polyakov <johnpol@2ka.mipt.ru>
Cc: Andi Kleen <andi@firstfloor.org>,
       Glenn Griffin <ggriffin.kernel@gmail.com>, netdev@vger.kernel.org,
       linux-kernel@vger.kernel.org
Subject: Re: [PATCH] Add IPv6 support to TCP SYN cookies
Message-ID: <20080205212017.5db50114@core>
In-Reply-To: <20080205203911.GA9891@2ka.mipt.ru>
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	<20080205203911.GA9891@2ka.mipt.ru>
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> How does syncookies prevent windows from growing?

Enabling them doesn't.

> 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).

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