NAGIOS CORE

Open Source IT Infrastructure Monitoring Tool

Trusted by 1M+ users worldwide, Nagios Core provides complete monitoring of your entire IT infrastructure environment – including websites, DNS, servers, routers, switches, services, servers, workstations, and more.

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What is Nagios Core?

Nagios Core is the world’s most trusted free, open source monitoring solution for IT infrastructure. Whether you’re managing a small business network or an enterprise data center, Nagios Core provides comprehensive monitoring of:

  • Servers – (Linux, Windows, Unix) – Monitor CPU, memory, disk, processes
  • Network Devices – Switches, routers, firewalls, load balancers
  • Websites & Applications – Uptime, response time, content verification
  • Services– DNS, DHCP, FTP, SSH, email, databases
  • Custom Metrics – Extensible with thousands of plugins
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Why Choose Nagios Core?

Proven Reliablity

Downloaded millions of times since 2002, Nagios Core is the industry standard for open source IT monitoring.

100% Free

No licensing costs, no hidden fees, no limitations. Completely free forever under GPL v2 license.

Highly Extensible

Works with thousands of community-developed plugins and integrations. Customize monitoring for any environment.

Enterprise-Grade

Trusted by Fortune 500 companies, government agencies, and organizations worldwide for mission-critical monitoring.

Nagios Core Source Code

For developers and advanced users who need complete control:

Full source code access for customization
Install on any Linux distribution
Build custom monitoring solutions
Contribute to open source development

The #1 Open Source Monitoring Solution For IT

Nagios Core has been downloaded  millions of times for good reason – it’s the industry standard in open source monitoring for all environments, large and small.

Websites & Web Applications

Monitor uptime, response time, SSL certificates, content changes

Servers & Workstations

Track CPU, memory, disk usage, running processes, system health

Network Infrastructure

Monitor switches, routers, firewalls, ports, bandwidth, traffic

Applications & Services

Database servers, email systems, DNS, DHCP, custom applications

Cloud Infrastructure

AWS, Azure, Google Cloud, and other cloud platforms

Custom Metrics

Anything you can measure with a script or plugin

System Requirements

Minimum requirements for Nagios Core

Hardware Requirements

  • CPU: 2 cores minimum (4+ recommended for larger deployments)
  • RAM: 2GB minimum (4GB+ recommended)
  • Disk: 20GB free space minimum
  • Network: Reliable network connectivity

Supported Linux Distributions

  • Ubuntu 20.04 LTS, 22.04 LTS, 24.04 LTS
  • CentOS 7, 8, Stream
  • Debian 10, 11, 12
  • Red Hat Enterprise Linux 7, 8, 9
  • Other Linux distributions (may require manual configuration)

Software Requirements

  • Web Server: Apache 2.x or Nginx
  • PHP: Version 7.0 or higher
  • C Compiler: GCC or compatible for building from source

Operating System

Linux-based OS (Ubuntu, CentOS, Debian, RHEL, or compatible)

Nagios Core vs Nagios XI - Which is Right for You?

Feature Nagios Core (Free) Nagios XI (Commercial)
Cost 100% Free Paid
License Open Source (GPL v2) Commercial
Configuration Text-based config files Web-based GUI
Setup Manual installation Automated wizards
Dashboards Basic web interface Advanced dashboards
Reports Basic reports Professional reports
Configuration Wizards Not Included Included
Support Community forums Professional support
Updates Manual Automatic
Backup/Restore Manual Automated
Best For IT pros comfortable with CLI Teams needing quick deployment

Bottom Line: Nagios Core is perfect for technical teams who want complete control and no licensing costs. Nagios XI is ideal for organizations that need a polished web interface and professional support.