From: Christian Grothoff <grothoff@in•tum.de>
To: Jacob Appelbaum <jacob@appelbaum•net>
Cc: Andi Kleen <andi@firstfloor•org>,
Stephen Hemminger <stephen@networkplumber•org>,
David Miller <davem@davemloft•net>,
netdev@vger•kernel.org, linux-kernel@vger•kernel.org,
knock@gnunet•org
Subject: Re: [PATCH] TCP: add option for silent port knocking with integrity protection
Date: Thu, 12 Dec 2013 12:43:59 +0100 [thread overview]
Message-ID: <52A9A17F.6050505@in.tum.de> (raw)
In-Reply-To: <52A98DBF.4090702@appelbaum.net>
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On 12/12/2013 11:19 AM, Jacob Appelbaum wrote:
> I think that generally, I would prefer if the code didn't use MD5 but
> otherwise, I don't see any real risk of adding an exploitable hole. It
> seems silly to disable it by default though - ideally, I'd like a sysctl
> to ensure that Tor could use this without making the user recompile
> their kernel. That is more of a pain than running a userspace helper, I
> think.
>
> All the best,
> Jacob
Given that the output is truncated to 32 bits and that performance (SYN
flood) is also a concern, AND that the original TCP SQN generation is
also MD5-based (and we want to look the same), what disadvantage do you
see over MD5? Given the truncation to 32 bits, I don't think a stronger
hash would do anything for us.
As for it being disabled by default, we did this with respect to
kernel submission guidelines which we understood said that features
should _initially_ always be submitted with disabled-by-default
(presumably so that until they have stabilized, nobody is harmed
unless they explicitly activate the code).
I don't see the point in having a sysctl, as applications have to
explicitly request it anyway.
-Christian
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next prev parent reply other threads:[~2013-12-12 11:43 UTC|newest]
Thread overview: 22+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-12-10 18:35 [PATCH] TCP: add option for silent port knocking with integrity protection Christian Grothoff
2013-12-11 20:01 ` David Miller
2013-12-11 20:19 ` Christian Grothoff
2013-12-11 20:26 ` Stephen Hemminger
2013-12-11 20:39 ` Christian Grothoff
2013-12-11 21:25 ` Andi Kleen
2013-12-11 22:53 ` Christian Grothoff
2013-12-12 1:23 ` Andi Kleen
2013-12-12 10:19 ` Jacob Appelbaum
2013-12-12 11:43 ` Christian Grothoff [this message]
2013-12-12 12:23 ` Jacob Appelbaum
2013-12-12 14:34 ` Eric Dumazet
2013-12-12 15:07 ` Christian Grothoff
2013-12-12 15:33 ` Eric Dumazet
2013-12-12 15:46 ` Hannes Frederic Sowa
2013-12-13 3:07 ` Hannes Frederic Sowa
2014-08-19 19:36 ` Alexander Holler
2014-08-20 8:24 ` Hagen Paul Pfeifer
2014-08-20 9:07 ` Alexander Holler
2014-08-20 9:28 ` Hagen Paul Pfeifer
2014-08-20 9:47 ` Alexander Holler
2014-08-20 10:20 ` Alexander Holler
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