Recently we have worked with a small company who was trying to determine the best tool to monitor their network. They had heard of Nagios and wanted to explore that option first. They also were most interested in an Open Source option as they did not want to have renew licenses to lower their ongoing cost. In this type of evaluation, there are a lot of things to consider.
1. Nagios Options
Nagios was built to be flexible and that flexibility has created a number of options that can be used for a frontend or an addon. Some of those options are free to use and some will cost a small fee. I say “small fee” because if you compare it to some of the major networking monitoring tools an organization can spend many thousands of dollars monitoring their network. In this consulting situation they wanted to narrow the field down to two options Nagios Core (the Open Source, free option) and Nagios XI which costs a modest fee per year for support and updates. Though there are other options out there, this is a good place to start because Nagios is under the hood in those other options that create a frontend.
2. Comparison: Nagios Core vs. Nagios XI
Nagios Core is the Open Source option for Nagios. It is powerful in that it can be used to monitor many different devices in a diverse setting. I have talked with administrators who are using Nagios Core to perform 5000 checks per second! For a small business that may not initially be the focus, but performance should be an indicator, as success in using this tool will lead to the decision to perform more checks. The next aspect to consider with Nagios Core is flexibility. What kind of devices do you want to monitor? Nagios can monitor switches, routers, wireless devices, Windows servers, Linux servers, applications on those devices, network bandwidth, etc. Nagios Core, like Nagios XI, is only limited by the administrators ability to implement the kind of check required.
One caveat for Nagios Core is that it will require intermediate skills at the Linux command line. If your organization does not have administrators with command line skills you will either need to get them training for the command line or take a close look at the second option, Nagios XI.
Nagios XI is a powerful Nagios option that is configured from a GUI, which make the transition to Nagios easier, I did not say easy. Any network monitoring tool requires a solid understanding of the devices you are monitoring. And though Nagios XI does present the graphical configuration options like wizards, reports, views, etc., it also requires some skill at the command line. Even with Nagios XI you may have to install Perl modules from the command line for instance if you select plugins that do not come with Nagios XI.
For faster implementation of network monitoring Nagios XI is your best choice if you are not skilled in using the command line. Nagios XI can ultimately be cheaper than Nagios Core if you value the time administrators take to set things up from the command line.
Ultimately, the best choice is what works in the long term for a company.