Nagios

Nagios is an open source Computer system monitoring, Network monitoring and infrastructure monitoring application. Nagios is a power full monitoring system that enables organization to identify and resolve IT infrastructure problems before they affect critical business processes.

Nagios is licensed under GNU General public licence version 2.

It provides the following features.

• Monitoring of network devices, services, systems, hosts, servers, protocols, applications etc. (SMTP, POP3, HTTP, NNTP, ICMP, SNMP, Processor load, disk usage, system logs).
• Monitoring of temperature and alarms, etc. which have the ability to send collected data via network to specifically written plugins.
• Alerts when critical infrastructure components fail and recover, providing administrator with notice of important events. Alters can be delivered via mail, sms, or custom scrips.
• Remote monitoring supported through SSH or SSL encrypted tunnels.
• Reports provide a historical record of outages, events, notifications and alert response for later review. Availability reports help ensure SLA's are being met.
• Trending and capacity planning addons ensure aware of aging infrastructure.
• Multi-user access to web interface to allows stack holders to view infrastructure status. user-specific views ensures clients see only their infrastructure components.

For more details and downloads click here.