Nagios allows both the monitoring of services on its own, and the receipt of information about computer and service statuses from other applications. Being able to send results directly to Nagios creates a lot of opportunities for extending how Nagios can be used.

Nagios can be integrated with external applications so that they report the status of certain hosts and services. It also allows applications to report the status of services that they use on the fly. This can be used to make Nagios instantly aware of any failures that occur within the IT infrastructure.

Passive checks can also be used for performing long-running tests and reporting the the results of these to Nagios. Active checks usually have a very short timeout for the check commands, whereas some tests require several minutes or even hours to complete. In such cases, it is possible to schedule them outside Nagios and report the results as passive checks.

Nagios also offers an additional component that can be used when...