Re: Seeking assistance deciphering NTP packet capture

Miroslav Lichvar <[email protected]>
Newsgroups gmane.comp.time.chrony.user
Message-ID <Yp21JY/3f+3hwh6m@localhost>
On Fri, Jun 03, 2022 at 07:43:07PM +0000, Bryan Evenson wrote:
> March 20, 1985 7:17:35 UTC
> July 31, 2036 00:19:20 UTC
> July 25, 2004, 05:41:48 UTC
> Feb 16, 2061 19:03:36 UTC
> 
> These were from packets send about one minute apart from each other.  On the server response, the Reference Timestamp, Receive Timestamp and the Transmit Timestamp were all reasonably close to each other and were based on current time.
> 
> Does someone know why the transmit timestamps are so far off from actual time?  Is this just a data translation problem where Wireshark is reading the field format incorrectly?

The client's transmit timestamps are completely random. The server
doesn't need to know client's time. It's indicated by the precision of
32 in the packet. It's a security and privacy feature described here:

https://datatracker.ietf.org/doc/html/draft-ietf-ntp-data-minimization-04

-- 
Miroslav Lichvar


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