TECH SOLUTIONS

There are several different configuration files that you're going to needto create or edit before you start monitoring anything.

Sample Configuration File

A sample main configuration file (/usr/local/nagios/etc/nagios.cfg) is installed

Config File Location

The main configuration file is usually named nagios.cfgand located in the /usr/local/nagios/etc/directory.

Configuration File Variables

Below you will finddescriptions of each main Nagios configuration file option...

Log File

Format:

log_file=

Example:

log_file=/usr/local/nagios/var/nagios.log

This variablespecifies where Nagios should create its main log file. This shouldbe the first variable that you define in your configuration file, asNagios will try to write errors that it finds in the rest of yourconfiguration data to this file.

Object Configuration File

Format:

cfg_file=

Example:

cfg_file=/usr/local/nagios/etc/hosts.cfg

cfg_file=/usr/local/nagios/etc/services.cfg

cfg_file=/usr/local/nagios/etc/commands.cfg

This directive isused to specify an object configuration file containing objectdefinitions that Nagios should use for monitoring. Objectconfiguration files contain definitions for hosts, host groups,contacts, contact groups, services, commands, etc. You can seperateyour configuration information into several files and specifymultiple cfg_file=statements to have each of them processed.

Object Configuration Directory

Format:

cfg_dir=

Example:

cfg_dir=/usr/local/nagios/etc/commands

cfg_dir=/usr/local/nagios/etc/services

cfg_dir=/usr/local/nagios/etc/hosts

This directive isused to specify a directory which contains object configuration filesthat Nagios should use for monitoring. All files in the directorywith a .cfgextension are processed as object config files. Additionally, Nagioswill recursively process all config files in subdirectories of thedirectory you specify here. You can seperate your configuration filesinto different directories and specify multiple cfg_dir=statements to have all config files in each directory processed.

Adding A New Host:

Create any directory

mkdir/usr/local/nagios/etc/config

Createa file:

sudo vi/usr/local/nagios/etc/config/hosts.cfg

And,add following lines per host:

definehost{

use linux-server

host_name jumbo01

alias jumbo01

address 192.168.1.134

contact_groups admins

}

Now edit your main config file to tell it the location of the new configfile:

sudo vi /usr/local/nagios/etc/nagios.cfg

Add thefollowing line to the file

cfg_dir=/usr/local/nagios/etc/config

Nowrestart your nagios daemon:

sudo /etc/init.d/nagios restart

definehost

Here we define a new host:

use:We use Linux-Server because its the easiest template to use, more onthis later

host_name:This is the host name, this is how you reference your hosts settings,it doesn’t have to be its address just something meaningful relatedto the host

alias:This is the long name for the host, this is only used for displaypurposes

address:This is important, its the actual address for the host, either a DNSname or IP address will work here.

Adding A New Service

Create a new file

sudo vi/usr/local/nagios/etc/config/services.cfg

And add followinglines for each service:

defineservice{

use generic-service

host_name jumbo01

service_description check_nimbus

normal_check_interval 1

retry_check_interval 1

contact_groups admins

notifications_enabled 1

notification_interval 960

notification_period 24x7

notification_options w,u,c,r

check_command check_nimbus_jumbo01

}

defineservice

This is were we define the services on each host, forgoogle we are only going to check if its alive(ping) and check to seeif its web server is running (http). We need to two services forthis, however the settings are the same for each:

useThis is the service template, use generic-serivce is the standardtemplate.

host_nameThis is where we reference what host we want the service connectedto, use the name of the host defined earlier.

service_descriptionThis is the name the user will see on thenagios web page

check_commandThis is the command we are going to run to test if the service isrunning, more on commands later.

So whatabout the nagios.cfg, why did we add that line to it, well as wecreated a new cfg file we need to tell nagios about it, you caneither have one massive file for each host or make a new file foreach one, however if you make a new file for each one you have to addit to the nagios.cfg.

Add Command Definition

Create a new file and add following lines per command:

sudo vi/usr/local/nagios/etc/config/command.cfg

definecommand {

command_name check_supervisor_jumbo01

command_line $USER1$/check_jumbo jumbo01 supervisor

}

WritePlugin:

Writethe plugin as per your requirement and save it in/usr/local/nagios/libexec directory.

Restart Nagios:

sudo /etc/init.d/nagios restart

Enjoy!

If youget any errors when restarting run the following command to check forproblems with your config files

sudo/usr/local/nagios/bin/nagios -v /usr/local/nagios/etc/nagios.cfg

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Configurationfor Email Notifications:

If you want to receive email notifications for Nagios alerts, you need to installthe mailx (Postfix) package.

sudo apt-get install mailx

sudo apt-get install postfix

You'll have to editthe Nagios email notification commands found in/usr/local/nagios/etc/objects/commands.cfgand change any '/bin/mail' references to '/usr/bin/mail'. Once you dothat you'll need to restart Nagios to make the configuration changeslive.

sudo /etc/init.d/nagios restart

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