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[ntpwg] Antw: Re: Antw: Re: Antw: Re: call for adoption (draft-dfranke-ntp-data-minimization)

"Ulrich Windl" <Ulrich.Windl@rz.uni-regensburg.de> Tue, 28 March 2017 14:26 UTC

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Date: Tue, 28 Mar 2017 16:26:27 +0200
From: Ulrich Windl <Ulrich.Windl@rz.uni-regensburg.de>
To: Daniel Franke <dfoxfranke@gmail.com>
References: <CA564C5C-6CED-4810-BA2F-5433F2525249@isoc.org> <20170327133842.GK8192@localhost> <58D9FD22020000A1000255AD@gwsmtp1.uni-regensburg.de> <4cff4cd7-1eec-0e72-b235-1a8d65fc7fc4@nwtime.org> <58DA0F83020000A1000255CF@gwsmtp1.uni-regensburg.de> <CAJm83bCvuJTqoiP8SeYSwEceiJe90C+V8+3AfdgczJ-+L1sa9Q@mail.gmail.com>
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Subject: [ntpwg] Antw: Re: Antw: Re: Antw: Re: call for adoption (draft-dfranke-ntp-data-minimization)
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>>> Daniel Franke <dfoxfranke@gmail.com> schrieb am 28.03.2017 um 16:08 in
Nachricht
<CAJm83bCvuJTqoiP8SeYSwEceiJe90C+V8+3AfdgczJ-+L1sa9Q@mail.gmail.com>:
> On 3/28/17, Ulrich Windl <Ulrich.Windl@rz.uni-regensburg.de> wrote:
>> IMHO it would be consistent to set precision to 3 (the lowest possible
>> precision (0.125s) where NTP will start to work) and use 29 bits of
>> randomness then. Still a half billion attack packets might transit without
>> being detected, but I doubt that.
> 
> 2**29 packets is about 541 gigabits including ethernet headers, so on
> a 1Gbps link is about a 0.18% chance of attacker success during the 1s
> MAXDIST window. On a 10Gbps link this becomes 1.8%. That's a big
> improvement over the status quo but still a non-negligible weakness.
> 
> What's the benefit of randomizing anything less than the full 64 bits?

IMHO, its just because ist named "transmit timestamp" and not NOUNCE.
(Be are talking about a SHOULD anyway, don't we? So anyone who feel insecure may fill pure random data)

Personally I'd be interested in a real system where NTP contributes most to make a system trackable.

Regards,
Ulrich





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