"Nagios is a free, open source enterprise monitoring tool designed to run on Linux. It has extensive monitoring and management capabilities that allow you to check applications, databases and network devices, as well as Windows and Unix/Linux hosts and services. It is easy to install, fast to configure and highly customizable.
"Nagios also comes with a Web-based console, extensible Nagios Event Broker (NEB), that allows you to integrate Nagios with other tools, like database back-ends, and a large collection of monitoring commands and capabilities..."
