Leap Second

[RW]

On Wed, 1 Jul 2015 21:52:46 -0400
Garrett Wollman wrote:

> <<On Thu, 2 Jul 2015 06:27:28 +1000, Peter Jeremy
> <peter at rulingia.com> said:
> 
> > ntpd(8) has provision for specifying a leapsecond file which
> > presumably makes it leap-second aware.  I haven't looked into the
> > details.
> 
> The current NTP protocol, as implemented by ntpd, distributes
> leap-second information if provided.  This information may be provided
> by higher-stratum (upstream) NTP servers, or by using the "leapfile"
> configuration statement in ntp.conf to specify a local copy of the
> leapseconds file in NIST/USNO format.  No such file is provided by
> default.  We could easily do so, but shouldn't, because that file
> would take precedence over the leap indicator learned from
> higher-stratum servers, and that's not desirable for clients.


I thought this sounded unlikely because the files have an explicit
expiry date, so I looked it up.

Apparently before 4.2.8 ntpd doesn't ignore expired leap-second files,
so they continue to take precedence over fresh information from other
servers.