[Ntp] Antw: [EXT] Re: Timescales, leapseconds and smearing

[Ulrich Windl <[e-mail]>]

>>> Martin Burnicki <martin.burnicki=[e-mail]> schrieb am
08.12.2020 um 18:29 in Nachricht
<[e-mail]>:

(I agree with Martin's points)

...
> At the other side of the transport are the operating systems. Most Unix
> systems just step the time back by 1 second to insert a leap second.

And the POSIX calls, while allowing "second 60" actually fail to return such as the kernel API cannot (AFAIK) provide the information necessary. In a perfect word "second 60" would be returned even when no NTP client is running on that machine.

...

> See my comments above. What should an NTP server do if a trusted source
> provides invalid information?

Before that, define how to detect that a trusted source is providing invalid information ;-)

...
> That would be similar to the times used in emails, where the main
> timestamp is some local time, but an offset allows to determine the
> associated UTC time.

But most notably those email time stamps lack information about the local clock error ;-)

...
> ntpd from ntp.org currently provides the current smear offset in a
> special interpretation of the refid field, if smearing is in progress.

Another "quick fix"...

Regards,
Ulrich