What This Book Covers

Chapter 1 talks about the Nagios application and system monitoring in general. It shows the benefits of using system monitoring software, and the advantages of Nagios in particular. It also introduces the basic concepts of Nagios.

Chapter 2 covers installing Nagios both when compiling from source code and when using pre-built packages. Details of how to configure users, hosts, and services are also given, as well as information on how Nagios sends notifications to users.

Chapter 3 talks about how to set up the Nagios Web interface, and what this offers to the user. It describes basic views for hosts and services, and detailed information on each individual item. It also introduces additional features such as scheduled downtimes, detailed information, and reports.

In Chapter 4, we go through Nagios plugins that allow the performing of checks of various services. It shows how you can check for standard services such as e-mail, Web, file, and database servers. It also describes how to monitor resources such as CPU usage, storage, and memory usage.

Chapter 5 focuses on managing large configurations and using templates. We see how dependencies between hosts and services can be defined, what are custom variables, and what adaptive monitoring is. We also look at flapping—services that start and stop randomly - and how Nagios detects this.

Chapter 6 describes the notification system in more details. It focuses on effective ways of communicating problems to users and how to set up problem escalations; it also shows how events work in Nagios and how they can be used to perform the automatic recovery of services.

Chapter 7 describes passive checks in detail. We give practical examples of when and how they can be used. It also shows how to use NSCA (Nagios Service Check Acceptor) for sending notifications.

Chapter 8 covers how Nagios checks can be run on remote machines. It walks through the details of deploying checks remotely over SSH using public-key authentication. It also shows how NRPE (Nagios Remote Plugin Executor) can be used for deploying plugins remotely.

In Chapter 9, we learn about SNMP (Simple Network Management Protocol) and how it can be used from Nagios. We start with an overview of SNMP and its versions; then we go through reading SNMP values from SNMP-aware devices and cover how this can then be used for performing checks from Nagios.

The first part of Chapter 10 looks at distributed monitoring. It talks about how Nagios can be set up on multiple hosts and how that information could be gathered on a central server. The second part of the chapter covers how to monitor computers that are running the Microsoft Windows operating system.

Chapter 11 shows you how to extend Nagios. We talk about how you can write your own check commands, add your own ways of notifying users, and use passive checks and NSCA to integrate your solutions with Nagios.