How to Configure Nagios monitoring server

Nagios is the most popular, open source, powerful monitoring system. It enables organizations to identify and resolve IT infrastructure problems before they affect critical business processes. With Nagios, you can monitor your remote hosts and their services remotely on a single window. It shows warnings and indicates if something goes wrong in your servers which eventually helps us to detect some problems before they occur. It helps us to reduce downtime and business losses. Nagios has capability of monitoring application, services, entire IT infrastructure.

Step 1: Prerequisites

• Install Web Server
• PHP
• MySQL Server

Firstly install all the required libraries that are dependent on nagios installation:

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

Start Services:

# service httpd start

Step 2: Create User Accounts & group

Now create a new nagios user account and setup a password to this account

# useradd nagios
# passwd nagios

Now create a groud for nagios setup “nagcmd” and add nagios user to this group. Also add nagios user in apache group.

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

Step 3: Install Nagios Core Service

After installing required dependencies and adding user accounts. Lets start with Nagios core installation. Download latest nagios core service from official site.

# cd /opt/
# wget http://prdownloads.sourceforge.net/sourceforge/nagios/nagios-4.0.8.tar.gz
# tar xzf nagios-4.0.8.tar.gz
# cd nagios-4.0.8
# ./configure --with-command-group=nagcmd
# make all
# make install
# make install-init
# make install-config
# make install-commandmode

Now use below command to setup apache configuration for Nagios installation.

# make install-webconf

Step 4: Configure Apache Authentication

We need to setup apache authentication for user nagiosadmin. Do not change this username. else you would required more changes in configuration.

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

Now restart Apache service to make the new settings take effect.

# service httpd restart

Step 5: Install Nagios Plugins

After installing and configuring Nagios core service, Download latest nagios-plugins source and install using following commands.

# cd /opt
# 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

Now compile and install nagios plugins

# ./configure --with-nagios-user=nagios --with-nagios-group=nagios
# make
# make install

Step 6: Verify and Start Nagios

Use the following commands to verify nagios install and start nagios core service.

# /usr/local/nagios/bin/nagios -v /usr/local/nagios/etc/nagios.cfg
# service nagios start

Also configure nagios service to start on system start

# chkconfig --add nagios
# chkconfig nagios on

Step 7: Install Centreon

Use the following commands to install Centreon.

# cd /usr/local/src
# wget http://download.centreon.com/centreon/centreon-2.3.8.tar.gz
# tar -zxf centreon-2.3.8.tar.gz
# cd centreon-2.3.8
# ./install.sh -i

Step 8: Test in Web Browser

Nagios creates its own apache configuration file /etc/httpd/conf.d/nagios.conf. There are no need to make any changes to it. Simply open below url in browser.
[change domain name with your domain or ip]

 http://Your-IP-Address/nagios/