ntpd doesn't synchronize to local clock (ntpd 4.2.8p4/xenial)

Bug #1558125 reported by Jonathan Sylvain on 2016-03-16
8
This bug affects 1 person
Affects Status Importance Assigned to Milestone
ntp (Ubuntu)
High
Unassigned

Bug Description

Ubuntu 16.04 (Xenial Xerus development branch)
ntpd version: 1:4.2.8p4+dfsg-3ubuntu3
Source available at: http://packages.ubuntu.com/source/xenial/ntp

Using the local clock as a source for ntpd doesn't work anymore

This appears to have already been fixed in 4.2.8p5 as per the bug report referenced below
http://bugs.ntp.org/show_bug.cgi?id=2965

Sample config extract from /etc/ntp.conf:
server 127.127.1.0
fudge 127.127.1.0 stratum 3

Results from ntpq, we would expected the server to be reachable and synced :
# ntpd -p
     remote refid st t when poll reach delay offset jitter
==============================================================================
 LOCAL(0) .LOCL. 3 l - 64 0 0.000 0.000 0.000

# ntpq
ntpq> as

ind assid status conf reach auth condition last_event cnt
=============================================
  1 4979 8011 yes no none reject mobilize 1

Changed in ntp (Ubuntu):
status: New → Triaged
importance: Undecided → High
tags: added: rls-x-incoming
Launchpad Janitor (janitor) wrote :

This bug was fixed in the package ntp - 1:4.2.8p4+dfsg-3ubuntu4

---------------
ntp (1:4.2.8p4+dfsg-3ubuntu4) xenial; urgency=medium

  * d/p/fix_local_sync.patch: fix local clock sync (LP: #1558125).

 -- Pierre-André MOREY <email address hidden> Thu, 17 Mar 2016 10:42:44 +0100

Changed in ntp (Ubuntu):
status: Triaged → Fix Released

Tested and confirmed it's working now.

There appears to be a behavioural change from 4.2.6 to 4.2.8 when using the local clock as a source.

In 4.2.6 the sync would be almost instantaneous while on 4.2.8 it will poll itself for a while before syncing as if it were an external resource.

I was able to overcome this delay by setting the local source as preferred

The new config in /etc/ntp.conf
server 127.127.1.0 prefer
fudge 127.127.1.0 stratum 3

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