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From: Florian Westphal <fw@strlen.de>
To: Jiri Bohac <jbohac@suse.cz>
Cc: Jakob Lell <jakob@jakoblell.com>,
	netdev@vger.kernel.org, davem@davemloft.net
Subject: Re: [PATCH 1/3] [RFC] TCP syncookies: slow down timer to mitigate spoofing attacks
Date: Fri, 16 Aug 2013 23:47:06 +0200	[thread overview]
Message-ID: <20130816214706.GF5154@breakpoint.cc> (raw)
In-Reply-To: <20130816000043.GA11950@midget.suse.cz>

Jiri Bohac <jbohac@suse.cz> wrote:
> This patch slows down the timer used in syncookies from 1/60 Hz to 1/60/4 Hz
> so that at any moment only two differrent timer values can be accepted.
> As a result, 1 bit of sequence number entropy is gained.
> 
> This changes the maximum cookie age limit from 4 - 5 minutes to 4 - 8 minutes.

I think we should just cap at 2 minutes (i.e, accept 0 and 1 minute delta).

A cookie is not validated if the last syn overflow is more than 3
seconds in the past anyway.

  parent reply	other threads:[~2013-08-16 22:31 UTC|newest]

Thread overview: 14+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2013-08-13 13:57 Quick Blind TCP Connection Spoofing with SYN Cookies Jakob Lell
2013-08-14 21:02 ` some one
2013-08-15 23:57 ` Jiri Bohac
2013-08-16  0:00   ` [PATCH 1/3] [RFC] TCP syncookies: slow down timer to mitigate spoofing attacks Jiri Bohac
2013-08-16  0:34     ` Neal Cardwell
2013-08-16  8:20       ` [PATCH v2 " Jiri Bohac
2013-08-16 21:47     ` Florian Westphal [this message]
2013-08-16  0:03   ` [PATCH 2/3] [RFC] TCP syncookies: introduce sysctl to configure the MSS tables Jiri Bohac
2013-08-16 21:40     ` Florian Westphal
2013-08-27 12:55       ` Jiri Bohac
2013-08-16  0:05   ` [PATCH 3/3] [RFC] TCP syncookies: only allow 3 MSS values by default to mitigate spoofing attacks Jiri Bohac
2013-08-16 21:31     ` Florian Westphal
2013-08-27 13:52       ` Jiri Bohac
2013-08-16  9:21   ` Quick Blind TCP Connection Spoofing with SYN Cookies Florian Westphal

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