Re: [Ntp] Antw: Re: Antw: Re: New rev of the NTP port randomization I-D (Fwd: New Version Notification for draft-gont-ntp-port-randomization-01.txt)

Harlan Stenn <stenn@nwtime.org> Wed, 29 May 2019 10:29 UTC

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From: Harlan Stenn <stenn@nwtime.org>
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Date: Wed, 29 May 2019 03:29:31 -0700
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Subject: Re: [Ntp] Antw: Re: Antw: Re: New rev of the NTP port randomization I-D (Fwd: New Version Notification for draft-gont-ntp-port-randomization-01.txt)
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On 5/29/2019 3:23 AM, Hal Murray wrote:
> 
> Ulrich.Windl@rz.uni-regensburg.de said:
>> I agree, but please don't treat it as 64-bit random value that is to be
>> guessed. 
> 
> It looks like 64 bits to me.  You don't need to put an actual time in that 
> slot.  Save the time, get a random number.  Put it in the packet and save it 
> too.  When a reply arrives, compare the "time stamp" in the packet with the 
> saved random number.  If they match, process using the saved time.
> 
> There was a draft describing that a year or so ago.

It's certainly a choice.

One that would prevent a friendly server from knowing how far off the
client's time really is.

-- 
Harlan Stenn, Network Time Foundation
http://nwtime.org - be a Member!