Learning Nagios 4 (2014)
Preface
The book is a practical guide to setting up Nagios 4, an open source network monitoring tool. It is a system that checks whether hosts and services are working properly and notifies users when problems occur. The book covers the installation and configuring of Nagios 4 on various operating systems, and it focuses on the Ubuntu Linux operating system.
The book takes the reader through all the steps of compiling Nagios from sources, installing, and configuring advanced features such as setting up redundant monitoring. It also mentions how to monitor various services such as e-mail, WWW, databases, and file sharing. The book describes what SNMP is and how it can be used to monitor various devices. It also gives the details of monitoring the Microsoft Windows computers. The book contains troubleshooting sections that aid the reader in case any problems arise while setting up the Nagios functionalities.
No previous experience with network monitoring is required, although it is assumed that the reader has a basic understanding of the Unix systems. It also mentions examples to extend Nagios in several languages such as Perl, Python, Tcl, and Java so that readers who are familiar with at least one of these technologies can benefit from extending Nagios. When you finish this book, you'll be able to set up Nagios to monitor your network and will have a good understanding of what can be monitored.
What this book covers
Chapter 1, Introducing Nagios, talks about Nagios 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, Installing Nagios 4, covers the installation of Nagios both when compiling from source code or using the prebuilt packages. Details on how to configure users, hosts, and services as well as information on how Nagios sends notifications to users are given in this chapter.
Chapter 3, Using the Nagios Web Interface, talks about how to set up and use the Nagios web interface. It describes the basic views for hosts and services and gives detailed information on each individual item. It also introduces some features such as adding comments, scheduled downtimes, viewing detailed information, and generating reports.
Chapter 4, Using the Nagios Plugins, goes through the standard set of Nagios plugins that allows you to perform 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, Advanced Configuration, focuses on the efficient management of large configurations and the use of templates. It shows how dependencies between hosts and services can be defined and discusses custom variables and adaptive monitoring. It also introduces the concept of flapping and how it detects services that start and stop frequently.
Chapter 6, Notifications and Events, describes the notification system in more details. It focuses on effective ways of communicating problems to the users and how to set up problem escalations. It also describes how events work in Nagios and how they can be used to perform automatic recovery of services.
Chapter 7, Passive Checks and NSCA, focuses on cases where external processes send results to Nagios. It introduces the concept of passive check, which is not scheduled and run by Nagios, and gives practical examples of when and how it can be used. It also shows how to use Nagios Service Check Acceptor (NSCA) to send notifications.
Chapter 8, Monitoring Remote Hosts, covers how Nagios checks can be run on remote machines. It walks through details of deploying checks remotely over SSH using public key authentication. It also shows how Nagios Remote Plugin Executor (NRPE) can be used for deploying plugins remotely.
Chapter 9, Monitoring using SNMP, describes how the Simple Network Management Protocol (SNMP) can be used from Nagios. It provides an overview of SNMP and its versions. It explains the reading of SNMP values from the SNMP-aware devices and covers how that can then be used to perform checks from Nagios.
Chapter 10, Advanced Monitoring, focuses on how Nagios can be set up on multiple hosts and how that information could be gathered on a central server. It also covers how to monitor computers that run the Microsoft Windows operating system.
Chapter 11, Programming Nagios, shows how to extend Nagios. It explains how to write custom check commands, how to create custom ways of notifying users, and how passive checks and NSCA can be used to integrate your solutions with Nagios. The chapter covers many programming languages to show how Nagios can be integrated with them.
Chapter 12, Using the Query Handler, focuses on the use of the Nagios query handler to send commands to Nagios as well as receive results and notifications from these commands. It shows how the query handler can be used from multiple programming languages and how it can be used to build an application to display Nagios updates in real time.
What you need for this book
This book requires a Linux server. As all of the examples are created using Ubuntu Linux, it is recommended that you use this distribution. The book goes through the process of setting up Nagios, so installing it is not a prerequisite of this book.
The Nagios web interface requires a web server. Chapter 3, Using the Nagios Web Interface, provides a step-by-step instruction on how to set up an Apache web server and configure it so that it be used with Nagios.
Who this book is for
The target readers of this book are System Administrators who are interested in using Nagios. This book will introduce Nagios along with the new features of Version 4.
Conventions
In this book, you will find a number of styles of text that distinguish between different kinds of information. Here are some examples of these styles, and an explanation of their meaning.
Code words in text, object names, folder names, filenames, file extensions, pathnames, dummy URLs, user input, and Twitter handles are shown as follows: "This service group consists of the mysql and pgsql services on the linuxbox01 host."
A block of code is set as follows:
define service{
host_name linuxbox01
service_description mysql
check_command check_ssh
servicegroups databaseservices
}
When we wish to draw your attention to a particular part of a code block, the relevant lines or items are set in bold:
define service{
host_name linuxbox01
service_description mysql
check_command check_ssh
servicegroups databaseservices
}
Any command-line input or output is written as follows:
# cp /usr/src/asterisk-addons/configs/cdr_mysql.conf.sample
/etc/asterisk/cdr_mysql.conf
New terms and important words are shown in bold. Words that you see on the screen, in menus or dialog boxes for example, appear in the text like this: "You should start by downloading the source tarball of the latest Nagios 4.x branch. It is available under theGet Nagios Core section."
Note
Warnings or important notes appear in a box like this.
Tip
Tips and tricks appear like this.