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Krisha Arya
Krisha Arya

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Nagios Core 4.4.6 Installation and Setup on Ubuntu VM

#webdev #nagios #ubuntu #installation

Introduction

Nagios is an open-source monitoring system that allows IT administrators to monitor servers, services, and network infrastructure. It provides real-time alerts for failures or threshold breaches, ensuring high availability and reliability. Nagios supports monitoring of host resources (CPU, memory, disk), network services (HTTP, FTP, SMTP), and custom applications.

Purpose of This Setup

The goal of this setup is to install Nagios Core with a web interface on Ubuntu VM to:

  • Monitor the health and performance of servers and services.
  • Receive alerts for system failures.
  • Provide a centralized dashboard for easy monitoring.
  • Gain practical experience with Linux system administration, service monitoring, and web-based dashboards.

1. System Update & Install Prerequisites 

sudo apt update
sudo apt install wget unzip curl openssl build-essential libgd-dev libssl-dev \
libapache2-mod-php php-gd php apache2
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  • Installs build tools, Apache web server, PHP, and required libraries.

2. Download & Extract Nagios Core 

cd /tmp
wget https://assets.nagios.com/downloads/nagioscore/releases/nagios-4.4.6.tar.gz
sudo tar -zxvf nagios-4.4.6.tar.gz
cd nagios-4.4.6
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3. Compile Nagios 

sudo ./configure
sudo make all
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  • Prepares the build environment and compiles Nagios.

4. Create Users & Groups 

sudo make install-groups-users
sudo usermod -a -G nagios www-data
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  • Creates nagios user and nagcmd group.
  • Adds Apache user www-data to nagios group for web command access.

5. Install Nagios Core 

sudo make install
sudo make install-commandmode
sudo make install-config
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  • Installs Nagios binaries, sets permissions, and copies default configuration files.

6. Install Web Interface 

sudo make install-webconf
sudo a2enmod rewrite
sudo a2enmod cgi
sudo systemctl restart apache2
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  • Installs Nagios web files and enables required Apache modules.

7. Configure Firewall 

sudo ufw allow apache
sudo ufw enable
sudo ufw reload
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  • Allows HTTP traffic to the Nagios web interface.

8. Set Up Web Authentication 

sudo htpasswd -c /usr/local/nagios/etc/htpasswd.users linuxhint
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  • Username: linuxhint
  • Password: (as entered during command)
  • Used to log in to the Nagios web dashboard.

9. Install Nagios Plugins 

cd /tmp
sudo wget https://nagios-plugins.org/download/nagios-plugins-2.3.3.tar.gz
sudo tar -zxvf nagios-plugins-2.3.3.tar.gz
cd nagios-plugins-2.3.3
sudo ./configure --with-nagios-user=nagios --with-nagios-group=nagios
sudo make install
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  • Plugins enable checks for CPU, memory, disk, network, and services.

10. Verify Nagios Configuration 

sudo /usr/local/nagios/bin/nagios -v /usr/local/nagios/etc/nagios.cfg
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  • Ensures all configuration files are correct before starting Nagios.
  • No errors should appear; check “Total Warnings” and “Total Errors”.

11. Start Nagios 

sudo systemctl start nagios
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Or manually:

sudo /usr/local/nagios/bin/nagios /usr/local/nagios/etc/nagios.cfg
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  • Starts Nagios monitoring service.

12. Find VM IP Address 

hostname -I
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  • Example output: 192.168.171.129
  • This is the IP to access the Nagios web interface from a browser.

13. Access Nagios Web Interface

Open your browser and go to:

http://<VM-IP>/nagios
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  • Replace <VM-IP> with the IP from the previous step.

  • Username: linuxhint

  • Password: (as set in htpasswd)

  • You will see the Nagios Core dashboard with hosts, services, and alerts.

Summary

This setup provides a fully functional Nagios monitoring environment:

  • Monitors system metrics, services, and network resources.
  • Provides real-time alerts to prevent downtime.
  • Web interface allows centralized monitoring and control.
  • Prepares users for practical IT monitoring and Linux administration skills.

Motto: “Monitor, Alert, and Maintain — Keeping IT systems healthy and reliable.”

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