[Nagiosplug-help] check_ntp

[Richard Mohr]

On Mon, 2007-11-05 at 14:13 -0500, jmacaranas at fxdd.com wrote:

> Where does check_ntp gets the offset? How does it compute the value?  

I suppose the first question to ask is if you are using the C or perl
version of check_ntp?

Looking at the perl plugin, it seems that check_ntp gets the offset by
running "ntpdate -q host1".  I looked at the C version, and it seems
that it might be doing something similar (although it computes the
offset itself rather than calling ntpdate).

> Doing an check_ntp –H host1 shows an offset which is different to the
> offset result of ntpdc –p host1

That would make sense.  If I remember correctly, ntpdc will tell you how
much the remote server is offset from the peers it syncs with.  Running
ntpdate shows the offset between the remote host and host you run the
ntpdate command from.

Hmmm.  If my explanation is correct, then in my mind check_ntp is
measuring the wrong offset.  I only care about how much the remote
server differs from its peers, not how much it differs from my Nagios
server.  Or maybe the plugin is measuring exactly what it intended, and
it simply failed to explain what it meant by "offset".

-- 
Rick Mohr
Systems Developer
Ohio Supercomputer Center