Nagios Core Administration Cookbook Second Edition

Nagios Core Administration Cookbook Second Edition - Second Edition

By : Tom Ryder

Buy this Book

Nagios Core Administration Cookbook Second Edition - Second Edition

By: Tom Ryder

Buy this Book

Overview of this book

Nagios Core is an open source monitoring framework suitable for any network that ensures both internal and customer-facing services are running correctly and manages notification and reporting behavior to diagnose and fix outages promptly. It allows very fine configuration of exactly when, where, what, and how to check network services to meet both the uptime goals of your network and systems team and the needs of your users. This book shows system and network administrators how to use Nagios Core to its fullest as a monitoring framework for checks on any kind of network services, from the smallest home network to much larger production multi-site services. You will discover that Nagios Core is capable of doing much more than pinging a host or to see whether websites respond. The recipes in this book will demonstrate how to leverage Nagios Core's advanced configuration, scripting hooks, reports, data retrieval, and extensibility to integrate it with your existing systems, and to make it the rock-solid center of your network monitoring world.

Nagios Core Administration Cookbook Second Edition

Credits

About the Author

About the Reviewer

www.PacktPub.com

Preface

Free Chapter

Understanding Hosts, Services, and Contacts

Introduction

Creating a new network host

Creating a new HTTP service

Creating a new e-mail contact

Verifying configuration

Creating a new hostgroup

Creating a new servicegroup

Creating a new contactgroup

Creating a new time period

Running a service on all hosts on a group

Working with Commands and Plugins

Creating a new command

Customizing an existing command

Using an alternative check command for hosts

Writing a new plugin from scratch

Implementing threshold checks in a plugin

Using macros as environment variables in a plugin

Working with Checks and States

Introduction

Specifying how frequently to check a host or service

Changing thresholds for PING RTT and packet loss

Changing thresholds for disk usage

Scheduling downtime for a host or service

Managing brief outages with flapping

Adjusting flapping percentage thresholds for a service

Configuring Notifications

Introduction

Configuring notification periods

Configuring notifications for groups

Choosing states for notification

Specifying the number of failed checks before notification

Automating contact rotation

Defining an escalation for repeated notifications

Defining a custom notification method

Filtering notifications based on a host or service value

Monitoring Methods

Introduction

Monitoring PING for any host

Monitoring SSH for any host

Checking an alternative SSH port

Monitoring mail services

Monitoring web services

Checking that a website returns a given string

Monitoring database services

Monitoring the output of an SNMP query

Monitoring a RAID or other hardware device

Creating an SNMP OID for monitoring

Enabling Remote Execution

Introduction

Monitoring local services on a remote machine with NRPE

Setting the listening address for NRPE

Setting allowed client hosts for NRPE

Creating new NRPE command definitions securely

Giving limited sudo(8) privileges to NRPE

Using check_by_ssh with key authentication instead of NRPE

Using check_mk instead of NRPE

Using the Web Interface

Introduction

Using the Tactical Overview

Viewing and interpreting availability reports

Viewing and interpreting trends

Viewing and interpreting notification history

Adding comments on hosts or services in the web interface

Viewing configuration in the web interface

Scheduling checks from the web interface

Acknowledging a problem via the web interface

Managing Network Layout

Introduction

Creating a network host hierarchy

Using the network map

Choosing icons for hosts

Establishing a host dependency

Establishing a service dependency

Monitoring individual nodes in a cluster

Using the network map as an overlay

Managing Configuration

Introduction

Grouping configuration files in directories

Keeping a configuration under version control

Configuring host roles using groups

Building groups using regular expressions

Using inheritance to simplify configuration

Defining macros in a resource file

Using another object's directives in a host or service check

Using custom directives

Dynamically building host definitions

Security and Performance

Introduction

Using authentication for the Nagios Core web interface

Using authenticated contacts

Writing debugging information to the Nagios log file

Monitoring Nagios performance with nagiostats

Setting up a redundant monitoring host

Automating and Extending Nagios Core

Introduction

Allowing and submitting passive checks

Submitting passive checks from a remote host with NSCA

Submitting passive checks in response to SNMP traps

Setting up an event handler script

Tracking host and service states with Nagiosgraph

Reading status in a MySQL database with NDOUtils

Reading status from a Unix socket with MK Livestatus

Writing customized Nagios Core reports

Getting extra visualizations with NagVis

Writing custom Nagios Core management scripts

Index

Customer Reviews

5 star

4 star

3 star

2 star

1 star

Verifying configuration

In this recipe, you'll learn the most basic step in debugging a Nagios Core configuration, which is to verify it. This is a very useful step to take before restarting the Nagios Core server to load an altered configuration because it will warn us about possible problems. This is a good recipe to follow if you're not able to start the Nagios Core server at any point because of configuration problems and instead get output like this:

# /etc/init.d/nagios reload
Running configuration check... CONFIG ERROR!  Check your Nagios configuration.

Getting ready

You should have a working Nagios Core 4.0 or better server running.

How to do it...

We can verify the Nagios Core configuration as follows:

Run the following command, substituting the path to the nagios binary and our primary nagios.cfg configuration file if necessary:
```
# /usr/local/nagios/bin/nagios -v /usr/local/nagios/etc/nagios.cfg
```
If the output is very long, it might be a good idea to pipe it through a pager program, such as less:
```
# /usr/local/nagios/bin/nagios -v /usr/local/nagios/etc/nagios.cfg | less
```
Inspect the output and look for warnings and problems. Here's an example of the part of the output we can expect if our configuration is correct:
If there's a problem of some sort, we might instead see lines like the following, which is just an example of a possible error; here, my configuration is wrong because I neglected to add a contact_name directive for a new contact:

How it works...

The configuration is parsed as though Nagios Core were about to start up, to check that the configuration all makes sense. It will run basic checks, such as looking for syntax errors, and will also check things such as having at least one host and service to monitor. Some of the things it reports are warnings, meaning that they're not necessarily problems, such as hosts not having any services monitored or not reporting to any contacts.

This is the quickest way to get an idea of whether the Nagios Core configuration is sane and will work correctly and whenever, there's trouble restarting the Nagios Core server, it's a good idea to check the output of this command.

There's more...

The program at /usr/local/nagios/bin/nagios is actually the same program that runs the Nagios Core server, but the -v part of the command is a switch for the program that, instead of starting the server, verifies the configuration and shows any problems with it. The second path is to the configuration file with which Nagios Core starts, which in turn imports configuration files for objects such as the contact, host, and service definitions.

Nagios Core Administration Cookbook Second Edition - Second Edition

By : Tom Ryder

Nagios Core Administration Cookbook Second Edition - Second Edition

By: Tom Ryder

Overview of this book

Related Content you might be interested in

Current Title:

Nagios Core Administration Cookbook Second Edition - Second Edition

Verifying configuration

Getting ready

How to do it...

How it works...

There's more...

See also