Nagios is a highly configurable monitoring platform. Basically it gives you the possibility to take any output and can monitor it!
It has a great community around it; it’s very well documented and has many, many plug-ins.
There is a free and a paid version available:
- The Core version gives you the possibility to make the installation in any way you want, but requires some knowledge on how you can get the things done.
- The paid version (current named Nagios XI) try’s to include a unified interface where the user can administrate the whole Nagios server in one interface.