Nagios is a host and service monitor designed to inform you of network
problems before your clients, end-users or managers do. 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.
NOTE: Nagios might not work on 64bit archs.