[ntp:questions] Conflicting information on packet field types

Jason Rabel jasonrabel99 at gmail.com
Fri Oct 19 22:11:48 UTC 2018

I'm writing my own little query script to decode NTP packets and I've come
across some conflicting information in the RFCs and other white papers that
I'm hoping an authoritative source would know the answer to.

Specifically for the 'Poll Interval' and 'Root Dispersion' fields in the
NTP packet, some documents say they are unsigned variables, others say they
are signed...

I would think both would be unsigned, however I believe Chrony can set
negative poll intervals in its configuration for sub-second querying, but I
don't know if it tries to send that negative value in its NTP packets. The
largest poll interval allowed is 17, so even if it was decoded as a signed
field it would (should) never have an issue.

I can't think of a reason for Root Dispersion to be negative... 0 would be
the best and I think max is clamped to 16?


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