This KB article addresses the following errors you may see in the nagios.log file:
[1504231962] wproc: Core Worker 68003: Failed to register iobroker for stdout
[1504231962] wproc: Core Worker 68003: Failed to register iobroker for stderr
[1504231962] Warning: Check of host 'SOME_HOST' did not exit properly!
[1504231962] HOST ALERT: SOME_HOST;UNREACHABLE;SOFT;1;(Host check did not exit properly)
Resolution
This problem can occur when custom operating system limits restrict the max number of processes that can be executed.
Custom limits are defined in the /etc/security/limits.conf file, here is an example of limits defined in openSUSE Leap 42.x:
# harden against fork-bombs
* hard nproc 1700
* soft nproc 1200
root hard nproc 3000
root soft nproc 1850
You will need to increase the hard and soft values to resolve the problems you are experiencing, for example:
# harden against fork-bombs
* hard nproc 10000
* soft nproc 10000
root hard nproc 10000
root soft nproc 10000
After making the changes it is recommended to reboot the operating system to ensure the limits are applied.
If the change does not fix the problem then you should increase the values again.
Final Thoughts
For any support related questions please visit the Nagios Support Forums at:
http://support.nagios.com/forum/
Article ID: 756
Created On: Wed, Sep 20, 2017 at 8:08 PM
Last Updated On: Wed, Sep 20, 2017 at 8:31 PM
Authored by: tlea
Online URL: https://support.nagios.com/kb/article/nagios-core-failed-to-register-iobroker-756.html