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Hrish
Asked: 2018-07-19 05:05:21 +0800 CST

Are there any commands I can use to ensure that the NTP service is running and is also responsive?

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Are there any commands I can use to ensure that the NTP service is running and is also responsive?

What I am planning to do it have some monitory & remediation scrip to ensure that a couple of services are running and are responsive and especially NTP. And if the service is not running or is not responsive then have it restart the service or check again, and if it still fails for 3 times send an alert email.

Thanks in Advance!

scripts autostart automation bash ntp

3 Answers

  1. Best Answer

    The answer is version specific, you can use official Ubuntu Server documentation for references.

    Ubuntu 14.04 LTS

    In 14.04 LTS official documentation recommends to use ntp / ntpdate (see page 49 of Ubuntu 14.04 LTS Server Guide):

    Ubuntu uses ntpdate and ntpd.

    So expected command would be service ntp status or similar.

    Ubuntu 16.04 LTS

    In 16.04 LTS official documentation says different (see page. 54 of 16.04 LTS server guide):

    Starting with Ubuntu 16.04 timedatectl / timesyncd (which are part of systemd) replace most of ntpdate / ntp

    Ubuntu 16.04 LTS I do not know about chrony, time serving is done with ntpd from ntp package. So here systemctl status ntp.service may be used to check server status.

    Ubuntu 18.04 LTS

    In 18.04 LTS as Rinzwind already answered chrony is used (see page. 56 of 18.04 LTS server guide).

    I expect that systemctl restart chrony.service may be used for status check.

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  2. chrony is the default for Ubuntu as of 18.04

    chrony is a versatile implementation of the Network Time Protocol (NTP). It can synchronise the system clock with NTP servers, reference clocks (e.g. GPS receiver), and manual input using wristwatch and keyboard. It can also operate as an NTPv4 (RFC 5905) server and peer to provide a time service to other computers in the network.

    By default, the Ubuntu package will come with the configuration file pointing at ntp.ubuntu.com and the ubuntu.pool.ntp.org as NTP pools to provide 6 dual-stack NTP sources and 2 additional IPv4-only sources.

    A simple

    chrony activity

    will return with a error number notice and how many sources are active, how many are inactive. Easy to code something around it; like a script or even a service.

    It also supports logging (default to syslog) by editing /etc/crony/chrony.conf.

    # Uncomment the following line to turn additional logging on
log measurements statistics tracking
# or for even more logs add additional items
log measurements statistics tracking rtc refclocks tempcomp

    Each of the words after "log" will trigger its own log in `/var/log/crony/.

    So that could also be used as a track&trace type of thing where you scan the log and trigger a mail on certain events or conditions.

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  3. While the first three seem to show that Chrony is working, the last command shows that there is still a problem:

    $ chronyc activity

    200 OK
3 sources online
0 sources offline
0 sources doing burst (return to online)
0 sources doing burst (return to offline)
0 sources with unknown address

    $ chronyc sources

    210 Number of sources = 3
MS Name/IP address         Stratum Poll Reach LastRx Last sample
===============================================================================
^- gowest.hojmark.net            2   6   373   114    -25ms[  +50ms] +/-   34ms
^* ntp0.nl.uu.net                1   6   377    48    -90ms[  -35ms] +/-   11ms
^- ntp0.rrze.uni-erlangen.de     1   6   377    49    -92ms[  -38ms] +/-   17ms

    $ chronyc sourcestats

    210 Number of sources = 3
Name/IP Address            NP  NR  Span  Frequency  Freq Skew  Offset  Std Dev
==============================================================================
gowest.hojmark.net          9   5   470     +1.011    179.782    +44us    15ms
ntp0.nl.uu.net              9   6   393    -38.165    336.029   +122us    25ms
ntp0.rrze.uni-erlangen.de  11   6   406     -7.706    167.145   -195us    15ms

    $ timedatectl

                   Local time: Thu 2021-09-16 12:05:31 UTC
           Universal time: Thu 2021-09-16 12:05:31 UTC
                 RTC time: n/a
                Time zone: Etc/UTC (UTC, +0000)
System clock synchronized: no
              NTP service: inactive
          RTC in local TZ: no
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