How to install Nagios in Centos, Red Hat & Fedora..

Nagios is a powerful monitoring system that enables organizations to identify and resolve IT infrastructure problems before they affect critical business processes.

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First launched in 1999, Nagios has grown to include thousands of projects developed by the worldwide Nagios community. Nagios is officially sponsored by Nagios Enterprises, which supports the community in a number of different ways through sales of its commercial products and services.

Installation of Nagios core 4.1.0rc1

Step 1: Install Required Packages and Dependencies..

# yum install -y httpd php gcc glibc glibc-common gd gd-devel make net-snmp

Step 2: Setup Users Accounts

Now add nagios user account and set password for this account

# useradd nagios
# passwd nagios

Now add a group for nagios ‘nagcmd’ and add nagios & apache’ users in this group

# groupadd nagcmd
# usermod -a -G nagcmd nagios
# usermod -a -G nagcmd apache

Step 4: Download and Install Nagios Core 4.1.0rc1

After completing all the prerequisites installing dependencies and adding user group download latest Nagios..

# cd /opt
# wget http://sourceforge.net/projects/nagios/files/nagios-4.x/nagios-4.1.0/nagios-4.1.0rc1.tar.gz/download?use_mirror=softlayer-sng

Now extract the downloaded package

# tar -xvf nagios-4.1.0rc1.tar.gz
# cd nagios-4.1.0rc1
# ./configure --with-command-group=nagcmd
# make all
# make install
# make install-init

Now Install & Configure Web Interface for Nagios

# make install-webconf

Step 5: Now Configure Apache Authentication
In this step we will setup password for user ‘nagiosadmin’.
Provide password for nagiosadmin.

# htpasswd -c /usr/local/nagios/etc/htpasswd.users nagiosadmin

Now restart the apache service for new settings take effects..

For Red Hat,Centos 6..

# service httpd restart

For Red Hat,Centos 7..

# systemctl restart httpd

Step 6: Install Nagios Plugins.

# wget http://nagios-plugins.org/download/nagios-plugins-2.0.3.tar.gz
# tar xzf nagios-plugins-2.0.3.tar.gz
# cd nagios-plugins-2.0.3
# ./configure --with-nagios-user=nagios --with-nagios-group=nagios
# make
# make install

Step 7: Verify Nagios Configuration Files and Start Nagios

# /usr/local/nagios/bin/nagios -v /usr/local/nagios/etc/nagios.cfg
# service nagios start (RHEL,Centos 6)
# systemctl restart start (RHEL,Centos 7)

Also configure nagios service to start on system start

 
# chkconfig --add nagios
# chkconfig nagios on (RHEL,Centos 6)
# systemctl enable nagios (RHEL,Centos 7)

Step 8: Login into Nagios Web Interface
Now your Nagios is ready run it in your browser with
“http://localhost/nagios” and provide the username ‘nagiosadmin’ and password.

(change localhost with your FQDN)