Nagios is one of the most popular Opensource Computer System Monitoring, Network Monitoring and IT Infrastructure Monitoring Software which prevents the critical issues in IT Infrastrucure and run it smoothly without any trouble. It monitors entire IT infrastructure such as servers, switches, applications, network and services which alerts when there is any trouble and as well as the recovery alerts of the system.


Nagios Features


  • Monitors the entire IT infrastructure
  • Spot the problems before they occur
  • Know immediately when problems arise
  • Shares availability of data with stakeholders
  • Detects security breaches
  • Plan and budget for IT upgrades
  • Reduces downtime and business losses
  • Automatic fix of the problems when they are detected

What’s New in Nagios core 4.0.8


  • JSON API output has been better aligned in a standard way, and the output size limits has been lifted
  • Check Scheduling has been modified to prevent the bunching checks at the start of their time period
  • Auto-rescheduling of checks has been re-implemented. This can be enabled from settings
  • Nagios 4.0.8 Change log
  • How it works

1) Prerequisites for Nagios

LAMP and below packages should be installed in your system to install Nagios.

2) Create User & Group Account for Nagios

Create new user account & group for nagios and assign the user to nagios group and also assign the apache user to nagios group.

3) Download Nagios and the Plugins

Navigate to /opt directory and download the latest version of nagios and nagios plugin.

4) Compile and Install Nagios

Use the below commands to compile and install Nagios in your system.

Note: Don’t start Nagios now – there are still more to be done.

5) Customize Configuration

The sample configuration file is installed at /usr/local/nagios/etc and it works fine, but we need to add our email id for Alerts. For that you need to modify the below file /usr/local/nagios/etc/objects/contacts.cfg.

6) Configure the Web Interface

Use the below commands to install Nagios web interface and it will drop the config file to Apache conf.d directory, while installation nagios web interface creates nagios web user called nagiosadmin and you need to set the password to access the interface.

Why do we get an error message ? any guess? Yes, everybody knows Ubuntu based distribution uses apache2 directory instead of httpd that’s why we’re getting that error message. So what to do now ? instead of httpd location we need to drop the nagios.conf file to /etc/apache2/sites-enabled/ directory. Use the below steps.

7) Compile and Install the Nagios Plugins

After Nagios core installation, you need to install the latest nagios plugin in your system.

8) Enable the rewrite apache module

Enable the rewrite apache module to access nagios without any issue.

9) Start Nagios

Before staring nagios, check nagios configuration file whether there is any error occurred and also add the service to system startup.

10) Access Nagios Web Interface

Navigate your browser to http://localhost/nagios or http://IP-Address/nagios or http://Domain-Name/nagios and enter the Username and Password which you created.


Nagios Home Page


Host list By default nagios monitor itself and we can add N number of hosts.


Service status checking


Manage your IT infrastructure with Nagios and minimize the downtime.

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