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

From: Alan Cox <[email-masked]>
Date: Tue, 5 Feb 2008 21:20:17 +0000

> 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).