nsclient++ intermittent connection refused on same subnet

Question

I have setup Nagios and nsclient++ on a number of my Windows servers. They are all in the same subnet so no routing or firewall stuff is taking place in between the endpoints, and I have verified that the firewalls on the servers are not causing trouble. The problem is that the scheduled checks sometimes fail with "connection refused" and sometimes work! It is a frustrating problem to resolve because I do not know what to look for.

One place I did look is in the nsclient++ logs, where I am seeing this recurring error:

...\trunk\modules\CheckSystem\PDHCollector.cpp:148: Failed to query performance counters: \238...

This sounds promising, but I couldn't find much on Google about this error as it pertains to NSClient++

@mdpc, thanks for the advice - what Nagios board are you referring to? — tacos_tacos_tacos, Oct 23 '12 at 20:47
have you checked if the nagios server is having timeouts on pings, are other service checks not based on nsclient like snmp or others causing problems? — , Oct 25 '12 at 18:34

score 0 · Accepted Answer · edited Oct 25 '12 at 16:39

Do you get any response from your windows server if you run this command on your nagios server?

./check_nrpe -H <nsclient++ server ip>

You should also check if your nagios server is in the allowed host under Settings.

[Settings]
allowed_hosts=[ nagios server ip]

This config file should be found under your installation file on your windows server named nsc.ini

If you need further help, read up the NSClient wiki found here

nsclient++ intermittent connection refused on same subnet

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