Nagios® is an Open Source enterprise grade host, service and network monitoring program. Nagios is a host and service monitor designed to alert network problems. Nagios is designed to run under linux but works fine under most *NIX variants as well. The monitoring daemon runs intermittent checks on hosts and services you specify using external “plugins” which return status information to Nagios. When problems are encountered, the daemon can send notifications out to administrative contacts in a variety of different ways (email, instant message, SMS, etc.). Current status information, historical logs, and reports can all be accessed via a web browser.