Nagios has many places where it can be extended with external scripts or applications. We have now learned how it can be used to fit you and your company's needs. We have also learned that Nagios is not bound to any specific language and that its real power comes from the fact that you can choose the language you'll use to program your code.

One way Nagios can be made to do what you want it to do is to create your own check commands, also known as check plugins. Adding your own commands makes it possible to perform checks using techniques that might not be available using the default Nagios plugin commands. In many cases, self-created plugins are used to perform specialized checks. In this, Nagios is still responsible for planning when to perform the tests and handling their results, but it is up to you to decide how the test is going to be performed.

A similar approach is to use passive checks and supply the check results to Nagios. In such a case, you are responsible for performing...