If you are a network or systems administrator, your primary goal is making sure those systems are up and running 24/7. To do this efficiently you need monitoring tools. If you are looking for a cost effective, flexible tool that also happens to be open source, then you might want to take a good look at one of the standard bearers for network monitoring in the open source community – Nagios.


  • Product: Nagios XI network monitoring tool
  • Operating system: Linux (or UNIX variant)
  • C compiler
  • TCP/IP configured for the network
  • License: GNU General Public License Version 2
  • Initial cost: Free download
  • Support: Support plans for the enterprise start at $2,495.
  • Additional vendor information
  • TechRepublic Photo Gallery

Who’s it for?

Nagios is relevant for any sized network. From SMB to Enterprise, Nagios can handle just about anything you have. But you will need a bit of patience, because, although Nagios is simple to install, making it really work for you can take some time and tweaking. There are configuration files to edit, plugins to add, and more.

What problem does it solve?

Nagios enables the network administrator to keep a very close watch on all systems on the network. But it doesn’t just randomly watch anything and everything – Nagios only watches what you set it up to watch. And when something goes wrong, Nagios will alert you.

Standout features

  • Incredible flexibility
  • Easy installation
  • Scalable
  • Easy to navigate web-interface
  • Plenty of plugins
  • Alert system
  • Event handlers help with problem remediation
  • Capacity planning and trending
  • Reporting system

What’s wrong?

The only issue Nagios has is that it does not auto-discover devices. You will have to configure each device you want to monitor by creating a configuration file for that device.

Competitive products

Bottom line for business

If you are ready and will to do a little work, Nagios will be an outstanding network monitoring tool. Not only will it do a remarkable job once up and running, you will find it very tweak-able to best suit your needs. Nagios is the perfect solution for any business looking for amazing features at zero cost.

User rating

Have you encountered or used Nagios? If so, what do you think? Rate your experience and compare the results to what other TechRepublic members think. Give your own personal review in the TechRepublic Community Forums or let us know if you think we left anything out in our review.

Read our field-tested reviews of hardware and software in TechRepublic’s Product Spotlight newsletter, delivered each Thursday. We explain who would use the product and describe what problem the product is designed to solve. Automatically sign up today!

Next Page (Photo Gallery) >>

The Nagios Welcome page

This screen is the welcome screen you will see upon logging in. As you can see, there are plenty of features ready to serve you.

Service commands

From this window you can enable and disable various features for a particular host – no editing of configuration files needed.

Service status

From a single screen you can see the service status of all of your hosts.

Host groups

You can combine hosts into groups which can make for easy at-a-glance monitoring. Here you can see “All Servers”, “Debian GNU/Linux Servers”, “HTTP Servers”, “Pingable Servers”, and “SSH Servers”.

Mouse over

By mousing over a host on the status map, you can get a quick glimpse of plenty of useful information.

Service problems

Click on the Service Problems link and you will quickly get a glimpse of all issues on your network.