[Xymon] BUG: ntpdate command used in Xymon takes 2+ seconds each in RHEL 7 (with ntp 4.2.6+)

[Matt Vander Werf]

Hello J.C., etc.

(Brief Summary)
I noticed a issue/bug in the way Xymon uses the ntpdate command for it's
built-in ntp checks. Each ntp test (using the ntpdate options hard-coded
into Xymon) takes >= 2 seconds to run in any OS that uses upstream ntp
version 4.2.6 or later, including RHEL 7. This is due to a 2 second delay
that was put in place in upstream ntp starting with version 4.2.6. While
RHEL 6 uses upstream ntp 4.2.6 in it's latest iteration, the behavior I'm
referring to was reverted by Red Hat when RHEL 6 moved from using version
4.2.4 to 4.2.6 in a minor release. This was because this kind of major
change in behavior was not desired in only a minor RHEL release. However,
in RHEL 7 it was acceptable to keep this behavior change in place since it
was a major OS release.

(Detailed (continued) Summary)
Initially, I thought it was a Red Hat issue, so a support ticket was opened
up with Red Hat to figure out what the issue was. The support person was
able to replicate the issue I was seeing and created a public Bugzilla bug
here: https://bugzilla.redhat.com/show_bug.cgi?id=1260140. The ntp package
maintainer for Red Hat replied saying this was intended behavior and while
reverted in RHEL 6, it would not be reverted in RHEL 7. I asked in the
support ticket why it was not going to be fixed in RHEL 7 and got this
response in the support ticket:

"The original ntp version shipped in RHEL6 was 4.2.4, which had ntpdate
that was fast, but violated the default 2s minimum spacing between
requests. An NTP server with enabled rate limiting would not respond more
than once to such client. In ntp 4.2.6 that bug was fixed by adding spacing
between the requests, which slows down the ntpdate operation. This change
in behavior was not acceptable for a minor RHEL6 release, so the bug was
restored in a patch. In RHEL7 as a new major release I think such change is
acceptable and ntpdate now works as upstream intended."

Please see public Bugzilla bug for additional links for reference of this
change in behavior.

(Request)
*It would be greatly appreciated if this could be fixed in upstream Xymon
ASAP! However, since my Xymon server was installed using Terabithia RPMs,
what is most important to me is to get an updated Terabithia RPM created
that I can use to update my Xymon server. I understand that a source code
patch has already been created for Debian Xymon here:
https://anonscm.debian.org/cgit/collab-maint/xymon.git/tree/debian/patches/workaround-changed-ntpdate-behaviour
(referenced in earlier mailing list post:
http://lists.xymon.com/pipermail/xymon/2015-September/042224.html). This
would work perfectly!!

However, since I am using Terabithia RPMs, it is not very easy to simply
apply this above patch and recompile the base source code and use that,
since I am I not using just the base source code.

Maybe a hotfix release of Xymon could be created and released sometime very
soon with this fix? Currently, I am unable to do all the ntp tests I would
like to do because it causes xymonnet to go over the 5 minute interval
time!....

In the meantime, would it be possible for someone (maybe J.C.) to create a
binary patch or something that I could apply to the current xymonnet binary
with the fix in the above patch? Just a thought...and would be extremely
appreciated!!


Thank you very much for your time and work you do to make Xymon a great
monitoring tool! I look forward to some fixes being applied to resolve this
issue with the ntp tests!


TL;DR:
ntp checks take WAY to long in Xymon using hard-coded ntpdate options, due
to change in ntpdate behavior starting in upstream ntp version 4.2.6. This
particularly affects Xymon servers running on RHEL 7 (and new releases in
the future). Hotfix needed in Xymon to fix this issue (see source code
patch above) ASAP! If possible, a binary patch to xymonnet binary would be
much preferred in the meantime! I am using Terabithia RPMs for my Xymon
server, so using above source code patch is not possible or desirable!

FYI: I am running Xymon 4.3.21-4.el7.terabithia for my Xymon server.

Thanks!!

--
Matt Vander Werf
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