[Nagios](https://www.nagios.org/) is a popular open-source monitoring system. It keeps an inventory of your servers and monitors them so you know your critical services are up and running, and prevent problems before they occur. In this tutorial, you’ll install Nagios 4 and configure it so you can monitor host resources via Nagios’ web interface. Choose your operating system below to get started.
How To Install Nagios 4 and Monitor Your Servers on Ubuntu 18.04
How To Install Nagios 4 and Monitor Your Servers on Ubuntu 16.04
How To Install Nagios 4 and Monitor Your Servers on Ubuntu 14.04