Learning Nagios 3.0 is a comprehensive configuration guide to monitor and maintain your network and systems. It is a practical guide to setting up the Nagios 3.0 open source network monitoring tool, installing and configuring Nagios 3 on various operating systems. It will help understand system monitoring and how Nagios works and to install and configure Nagios to administer your network and system. Nagios 3 is a system that watches to see whether hosts and services are working properly, and notifies users when problems occur. Nagios is a tool for system and network monitoring. It constantly checks other machines and various services on those machines. The main purpose of system monitoring is to detect and report any system not working properly as soon as possible—so that you are aware of problems before a user runs into them. It is a modular and flexible solution that uses plug-ins to do its job.Nagios allows both the monitoring of services on its own, and the receipt of information about computer and service statuses from other applications.

The book is a beginner-level book, which will introduce Nagios to System Administrators who are interested in monitoring their systems.  It is an introduction to Nagios that will teach readers to use Nagios with its advanced features. At the same time, readers who have already used earlier versions of Nagios will also benefit because they will learn about the new and advanced features of Nagios 3. The focus is on teaching system administrators to secure their systems in a much improved manner incorporating the newer features of Nagios.It will teach Nagios beginners the basics of installation and configuration of version 3; it will show professionals who have already worked on earlier versions of Nagios the new features of Nagios like inheritance and also the new internal functions like better check scheduling.

The book will help learn, to notify users of current and future incidents to protect the availability, performance, and security of monitored asset, to pass service and host check results over the network using NSCA. One would also be able to set up a working and usable distributed monitoring system using NSClient++ and NC_Net and develop custom plug-ins responsible for doing the checks and analyzing result. Remot checks can be done using SSH and NRPE. SNMP can be used to retrieve information from a device, set options, and also cover means for a device to notify other machines about a failure

To read more about the book; http://www.packtpub.com/guide-for-learning-nagios-3/book