[tz] leap_second.list not updated after latest IERS Bulletin C

Paul Eggert eggert at cs.ucla.edu
Fri Dec 8 02:29:51 UTC 2023

On 12/7/23 13:21, Geert Hendrickx wrote:
> NTPsec logs the following at startup:
> CLOCK: leapsecond file ('/etc/ntp/leap-seconds.list'): good hash signature
> CLOCK: leapsecond file ('/etc/ntp/leap-seconds.list'): loaded, expire=2024-06-28T00:00Z last=2017-01-01T00:00Z ofs=37
> So I *guess* (without having looked at the code) that it actually cares
> about the expiration date as well.

I think you're right NTPsec does care, though I vaguely recall that if 
the file has expired the only issue is an unwanted log message.

If people are running NTPsec and configuring it to use TZDB's 
leap-seconds.list, that unwanted log message could be an issue. I just 
now checked the NTPsec source code, though, and by default it uses this URL:


which hasn't worked in a while; the contents are simply "ietf.org is no 
longer serving this file." So it may be that we don't need to issue a 
new TZDB release merely because 2023c's leap-seconds.list will be 
out-of-date soon.

> (but we periodically download it from IERS, not from TZ)

In that case your setup is OK as-is, though we may still need to hear 
from other people to see whether they're relying on the TZDB copy of 

TZDB uses the NIST version of leap-seconds.list rather than the IERS 
version, as the NIST version is clearly public domain and so this way we 
don't have to worry about copyright issues. However, the IERS version 
should work fine with either NTPsec or with other downstream uses, such 
as TZDB itself (that is, if you're not worried about copyright).

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