From: Frans Pop <elendil@planet•nl>
To: Olaf van der Spek <olafvdspek@gmail•com>, netdev@vger•kernel.org
Cc: linux-kernel@vger•kernel.org
Subject: Re: Enable syn cookies by default
Date: Sun, 11 Oct 2009 12:26:43 +0200 [thread overview]
Message-ID: <200910111226.44828.elendil@planet.nl> (raw)
In-Reply-To: <b2cc26e40910100601q7aed04acjcc9973ef06e6458f@mail.gmail.com>
This question is better asked on the kernel network development list.
Original mail from Olaf below.
Cheers,
FJP
=================
Hi,
I'm forwarding Debian feature request #520668.
Could syn cookies be enabled by default?
AFAIK syn cookies only get send when the half-open TCP connection
queue is full. So stuff like window scaling should work fine in normal
situations.
Speaking of which:
When the half-open TCP connection queue is full and syn cookies are
enabled, you get a message like "kernel: possible SYN flooding on port
2710. Sending cookies."
However when syn cookies are disabled, you don't get any message (in
kern.log), although connections to your server are timing out.
Could such a message be added?
Maybe with a suggestion to increase the size of that queue or to
enable syn cookies.
Greetings,
Olaf
http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=520668
http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=520667
https://bugs.launchpad.net/ubuntu/+bug/57091
next parent reply other threads:[~2009-10-11 10:27 UTC|newest]
Thread overview: 20+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <b2cc26e40910100601q7aed04acjcc9973ef06e6458f@mail.gmail.com>
2009-10-11 10:26 ` Frans Pop [this message]
2009-10-15 8:59 ` Enable syn cookies by default Olaf van der Spek
2009-10-16 8:55 ` Jarek Poplawski
2009-10-16 19:01 ` Jarek Poplawski
2009-10-16 19:56 ` Florian Westphal
2009-10-16 19:49 ` [PATCH 1/2] syncookies: print synflood warning if syn queue is full Florian Westphal
2009-10-16 19:51 ` [PATCH 2/2] syncookies: enable by default Florian Westphal
2009-12-08 14:47 ` [PATCH 1/2] syncookies: print synflood warning if syn queue is full Olaf van der Spek
2009-12-08 21:09 ` David Miller
2010-01-27 17:01 ` Olaf van der Spek
2009-10-21 7:17 ` Enable syn cookies by default Olaf van der Spek
2009-10-21 7:25 ` Eric Dumazet
2009-10-21 7:48 ` Olaf van der Spek
2009-10-21 9:16 ` William Allen Simpson
2009-10-21 10:10 ` Olaf van der Spek
2009-10-21 18:36 ` William Allen Simpson
2009-10-21 18:45 ` Olaf van der Spek
2009-10-21 13:04 ` David Miller
2009-10-21 18:04 ` William Allen Simpson
2009-11-13 12:42 ` Olaf van der Spek
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