Munin_(network_monitoring_application)
Munin is a free and open-source computer system monitoring, network monitoring, and infrastructure monitoring software application.[4]
Munin is written in Perl and uses RRDtool to create graphs,[5] which are accessible over a web interface. Its emphasis is on plug and play capabilities. About 500 monitoring plugins are currently available. It is intended to make it easy to determine "what's different today" when a performance problem happens and to provide visibility into capacity and utilization of resources.