Nagios is a very powerful platform because it is easy to extend. The previous chapters talked about the check command plugins and how they can be used to check any host or service that your company might be using. Another great feature that Nagios offers is the ability for third-party software or other Nagios instances to report information on the status of services or hosts. This way, Nagios does not need to schedule and run checks by itself; other applications can report information as it is available to them. In this chapter we will cover the following topics:
Understanding the difference between active and passive checks
Setting up passive checks in Nagios as well as enabling them for specific hosts and services
Troubleshooting common errors related to passive checks
An overview of what NSCA is
Setting up the NSCA server to allow receiving check results
Submitting host and service check results using the NSCA client binary
Configuring NSCA for secure communication...