[ntp:questions] [ntp:hackers] ntpdate removal is coming

Warner Losh imp at bsdimp.com
Sun Jul 17 21:33:17 UTC 2011

On Jul 17, 2011, at 1:57 PM, Harlan Stenn wrote:

> Dave Hart wrote:
>> After many years of deprecation while still shipping, ntpdate's days
>> as a separate C program are numbered.  I want to review alternatives
>> and suggest next steps.
>> First, though, a quick review of why ntpdate is deprecated and will be
>> removed.  ntpdate serves two primary purposes today:
>> 1)  A diagnostic tool, particularly to help troubleshoot connectivity
>> problems such as those introduced by firewalls.  In this role, 4.2.7's
>> sntp provides equivalent capability, including the ability to send
>> queries from the reserved NTP UDP port 123.
>> 2)  One-shot clock synchronization, such as before starting
>> step-phobic daemons.  In this role, there are a plethora of
>> alternatives, which I will cover below.
> Just to be clear, there *used* to be some reasons to set the clock
> before starting ntpd.  In general, there is no need to do this anymore
> and I have not heard any good reasons it should still be needed.
> If anybody knows of any *good* reasons to set the clock before starting
> ntpd, please speak up.

ntpdate was used to get sub-second synchronization at the cost of about a second of delay in startup.  ntpd would take a lot longer to do this, and would have problems with steps.  Most daemons hate it when time jumps too much, so this was a good compromise.  Does ntpd still dial in the frequency error before doing the phase shift that's patently obvious at startup?  If so, then there's still a need for ntpdate.  ntpd would also used to start asynchronously, meaning that it was a crap shoot if your daemons would see a a big time-step or not after they started.

If these problems have been corrected completely, then maybe ntpdate can be killed.  Otherwise, there's still a need for it.


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