Nagios

Nagios is a powerful monitoring system that enables organizations to identify and resolve IT infrastructure problems before they affect critical business processes.

Nagios monitors your entire IT infrastructure to ensure systems, applications, services, and business processes are functioning properly. In the event of a failure, Nagios can alert technical staff of the problem, allowing them to begin remediation processes before outages affect business processes, end-users, or customers. With Nagios youll never be left having to explain why a unseen infrastructure outage hurt your organizations bottom line.

Nagios Core is the free Open Source monitoring and alerting engine that serves as the primary application around which thousands of Nagios projects are built.