[Ntp] Comments on dratf-ietf-ntp-chronos-02

Watson Ladd <watsonbladd@gmail.com> Fri, 05 March 2021 20:12 UTC

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From: Watson Ladd <watsonbladd@gmail.com>
Date: Fri, 5 Mar 2021 12:12:24 -0800
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To: NTP WG <ntp@ietf.org>
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Subject: [Ntp] Comments on dratf-ietf-ntp-chronos-02
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Dear NTP WG,

One minor editorial comment: would be nice to include the recommended
parameters in the table for ease of readers. I had to go searching to
see them.

This draft seems to imply that the pool is being used. Otherwise the
requerying doesn't produce more servers. Reachability and increased
load on a volunteer shared resource are questions that need to be
addressed. We're happy to handle every device on the internet if it's
well behaved, but most parties in the pool cannot. Gathering can be a
passive DNS based approach, but this runs into potential caching
issues.

I also take issue with the assertion that chronos addresses network
adversaries. Nothing prevents a network adversary from controlling all
packets with dst=123 and shifting the time except authentication.
Chronos only solves byzantine attackers, which authentication of
trusted time servers also does. That's not to say it isn't useful, but
I think the claims are too broad.

Sincerely,
Watson Ladd

-- 
Astra mortemque praestare gradatim