Nagios Core is one of the most famous monitoring engines ever. Nagios was also the default monitoring engine of openITCOCKPIT for years. Our Team has tons of experiences within the whole Nagios universe.

openITCOCKPIT users do not interact with the underlying monitoring core at all. Version updates or configuration changes are all handled by openITCOCKPIT.

https://github.com/NagiosEnterprises/nagioscore