Subject: [Ntp] Robert Wilton's No Objection on draft-ietf-ntp-port-randomization-06: (with COMMENT)

From: Robert Wilton via Datatracker <[email-masked]>
Date: Wed, 02 Jun 2021 03:54:03 -0700

Robert Wilton has entered the following ballot position for
draft-ietf-ntp-port-randomization-06: No Objection

When responding, please keep the subject line intact and reply to all
email addresses included in the To and CC lines. (Feel free to cut this
introductory paragraph, however.)

Please refer to https://www.ietf.org/iesg/statement/discuss-criteria.html
for more information about DISCUSS and COMMENT positions.

The document, along with other ballot positions, can be found here:
https://datatracker.ietf.org/doc/draft-ietf-ntp-port-randomization/

----------------------------------------------------------------------
COMMENT:
----------------------------------------------------------------------

Hi,

Thanks for this document.

Like Ben's comment, I was wondering why the document doesn't give a stronger
recommendation as to which of the two approaches to follow.  It looks like all
the implementations that the document lists already take the per-association
approach, and that approach seems to be sufficient.   Hence, would it not be
simpler to make that the RECOMMENDED approach, and then say that
implementations MAY do per request randomization, but need to be aware that
individual requests are more likely to take different paths with different
latencies?

Thanks,
Rob

---

From: Miroslav Lichvar <[email-masked]>
Date: Wed, 2 Jun 2021 13:42:14 +0200

> individual requests are more likely to take different paths with different

Both approaches have some disadvantages, which may have a different
impact depending on the implementation (e.g. it's filtering
capabilities), so it's difficult to make a general recommendation. 

The implementations mentioned in the document don't use the same
approach. OpenNTPD and nwtime.org sntp seem to use the per-session
approach, but chrony by default uses the per-request approach. Another
widely used client using the per-request approach is the busybox ntpd.

-- 
Miroslav Lichvar