[Pkg-nagios-devel] Bug#865403: monitoring-plugins-basic: check_ntp fails with stretch version of ntpd

[Christoph Biedl]

Package: monitoring-plugins-basic
Version: 2.2-3
Severity: important

Dear Maintainer,

not unusual, I use check_ntp to probe a few ntp servers. After the
first of them was upgraded to stretch, the check fails with "NTP
CRITICAL: Offset unknown".

Some more investigation led me to the assumption ntpd implements a
strict rate limiting now, and check_ntp manages to trigger this.

How to repeat: Where $server is an ntpd in stretch, run (see #509359
why the LANG setting is necessary)

  LANG=C /usr/lib/nagios/plugins/check_ntp -4 -H $server -w 0.5 -c 0.8

Expected output (numbers may differ):

  NTP OK: Offset 0.001221060753 secs|offset=0.001221s;0.500000;0.800000;

Actual output:

  NTP CRITICAL: Offset unknown|

Running

  ntpdate -u -q $server

afterwards results in

  $time ntpdate[1234]: $server rate limit response from server.
  server $server, stratum 0, offset 0.000000, delay 0.00000

Also tcpdump shows pretty obvious the server just stops replying.


This affects both the jessie and stretch version of check_ntp, I haven't
checked older ones.

Although technically this could be worked around by changing the ntpd
configuration, I guess it's saner to address this in check_ntp, probably
by just placing a sleep in the right place. Please handle this in jessie
and stretch as well in a point release as people likely run their
monitoring applications on stable Debian releases.

Regards,

    Christoph

-- System Information:
Debian Release: 9.0
  APT prefers proposed-updates
  APT policy: (500, 'proposed-updates'), (500, 'stable')
Architecture: amd64 (x86_64)

Kernel: Linux 4.9.31 (SMP w/4 CPU cores)
Locale: LANG=en_US.UTF-8, LC_CTYPE=en_US.UTF-8 (charmap=UTF-8), LANGUAGE=en_US.UTF-8 (charmap=UTF-8)
Shell: /bin/sh linked to /bin/dash
Init: unable to detect

Versions of packages monitoring-plugins-basic depends on:
ii  iputils-ping               3:20161105-1
ii  libc6                      2.24-11+deb9u1
ii  libssl1.1                  1.1.0f-3
ii  monitoring-plugins-common  2.2-3
ii  procps                     2:3.3.12-3
ii  ucf                        3.0036

Versions of packages monitoring-plugins-basic recommends:
ii  libcap2-bin  1:2.25-1

Versions of packages monitoring-plugins-basic suggests:
pn  icinga | icinga2  <none>

-- no debconf information

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