Packt Publishing is giving away a free tutorial from the book Learning Nagios 3.0 titled "Passive Checks and NSCA."
This chapter describes passive checks in detail, along with practical examples of when and how they can be used. It also shows how to use NSCA (Nagios Service Check Acceptor) for sending notifications. You could read the complete tutorial here: Passive Checks and NSCA
For more information on the book please visit: packtpub.com/guide-for-learn ... ios-3/book