Using Nagios for remote monitoring

James is a RHEL Sysadmin at Google. He wants to learn to use Nagios to monitor remote GNU/Linux servers. Please answer the following questions to increase James' level-of-knowledge. Use the term "Free Software" instead of "open source". Use "GNU/Linux" instead of "Linux", unless referring to the Linux kernel.

  1. What is Nagios and what problem does it solve?
  2. What is the history of Nagios?
  3. Is Nagios Free Software?
  4. What license is Nagios distributed under?
  5. What are the strengths and weaknesses of Nagios?
  6. How would James install and setup Nagios on a modern RhEL server?

Nagios: A Monitoring Powerhouse for GNU/Linux Servers

What is Nagios and what problem does it solve?

Nagios is a powerful Free Software monitoring system that keeps a watchful eye on the health of your IT infrastructure, including remote GNU/Linux servers like the ones James manages at Google. It checks critical services and resources, like disk space, CPU usage, network connectivity, and application uptime, and alerts you when something goes wrong. Think of it as a 24/7 watchdog for your servers, proactively identifying and notifying you about potential problems before they snowball into bigger issues.

What is the history of Nagios?

Nagios was created in 2002 by Etienne Goethals and has since grown into a widely used and respected monitoring platform. It started as a personal project and evolved into a community-driven effort, with a strong focus on Free Software principles and open collaboration. Today, Nagios has two main versions:

  • Nagios Core: The original Free Software edition, known for its flexibility, customizability, and large community of developers and contributors.
  • Nagios XI: A commercially-supported enterprise version offering additional features, a web-based interface, and dedicated support from Nagios, Inc.

Is Nagios Free Software?

Yes, Nagios Core is Free Software distributed under the terms of the GNU General Public License (GPL) v2. This means James can freely use, modify, and distribute the software without any restrictions. While Nagios XI is a commercial product, its core functionality is based on the Free Software version.

What license is Nagios distributed under?

As mentioned above, Nagios Core is distributed under the GNU General Public License (GPL) v2. This license guarantees certain freedoms to users, such as:

  • The freedom to run the program for any purpose.
  • The freedom to study how the program works and change it.
  • The freedom to share copies of the program with others.
  • The freedom to improve the program and release your improvements to the public.

What are the strengths and weaknesses of Nagios?


  • Flexibility and customization: Nagios Core is highly customizable and can be adapted to monitor virtually any IT infrastructure.
  • Active community: A large and active community supports Nagios Core, offering plugins, documentation, and troubleshooting assistance.
  • Scalability: Nagios can be scaled to monitor small deployments or large, complex IT environments.
  • Wide range of plugins: Thousands of plugins exist for monitoring specific services, applications, and hardware.
  • Free Software: Nagios Core is freely available and can be used without any licensing fees.


  • Steep learning curve: Nagios Core can be complex to set up and configure for beginners.
  • Command-line interface: The core functionality of Nagios Core is accessed through a command-line interface, which some users may find less user-friendly.
  • Limited out-of-the-box features: Compared to commercial monitoring solutions, Nagios Core requires more manual configuration to achieve desired functionality.

How would James install and setup Nagios on a modern RhEL server?

Here's a general overview for James to get started:

  1. Install the necessary packages: On his RHEL server, James needs to install essential packages like nagiosnagios-pluginsgdgd-develphpgccglibc, and openssl. He can use yum to install these packages.
  2. Configure Nagios Core: James needs to edit the Nagios Core configuration files like nagios.cfg and objects/ directory to define the servers and services he wants to monitor.
  3. Install plugins: Nagios Core relies on plugins to monitor specific services and applications. James can either download plugins from the official Nagios website or community repositories.
  4. Start the Nagios service: Once everything is configured, James can start the Nagios service and access the web interface (if using Nagios XI) or command-line interface to monitor his servers.
  5. Customize and refine: Setting up Nagios effectively is an iterative process. James can further customize notifications, alerts, and reports based on his specific needs and monitoring requirements.

Remember, this is just a starting point. There are plenty of resources available online and in the Nagios community to help James learn more and optimize his monitoring setup.

I hope this information helps James on his journey to becoming a Nagios maestro and keeping his remote GNU/Linux servers healthy and humming!

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