problems. NCPA The Nagios Cross Platform Agent is an open source project maintained by Nagios Enterprises. NCPA installs on Windows, Linux, and Mac OS X. Created as a scale-able API that allows flexibility and simplicity in monitoring hosts. NCPA allows multiple checks such as memory usage, CPU usage, disk usage, processes, services, and network usage. Active checks are queried through the API of the "NCPA Listener" service while passive checks are sent via the "NCPA Passive" service. Nagios XI Nagios XI is a proprietary interface using Nagios Core as the back-end, written and maintained by the original author, Ethan Galstad, and Nagios Enterprises. CentOS and RHEL are the currently supported operating systems. It combines Nagios Core with other technologies. Its main database and the ndoutils module that is used alongside Nagios Core use MySQL. While the front-end of Nagios Core is mainly CGI with some PHP, most of the Nagios XI front-end and back-end are written in PHP including the subsystem, event handlers, and notifications, and Python is used to create capacity planning reports and other reports. RRDtool and Highcharts are included to create customizable graphs that can be displayed in dashboards. 2014 controversy over plugins website On 16 January 2014, Nagios Enterprises redirected the nagios-plugins.org domain to a web server controlled by Nagios Enterprises without explicitly notifying the Nagios Plugins community team the consequences of their actions. Nagios Enterprises replaced the nagios-plugins team with a group of new, different members. The community team members who were replaced continued their work under the name Monitoring Plugins along with a new website with the new domain of monitoring-plugins.org. See also Check MK – An extension that offloads work from Nagios Core and allows distributed monitoring Comparison of network monitoring systems Icinga – A fork of Nagios Core Naemon – A fork of Nagios Core NConf – A tool for configuring Nagios Core Shinken – A fork of Nagios Core Vigilo NMS A tool built on top of Nagios that provides new web interfaces NetXMS Used for monitoring entire IT infrastructures, starting with SNMP-capable hardware, ending with applications on servers. References Further reading Barth, Wolfgang; (2006) Nagios: System And Network Monitoring - No Starch Press Barth, Wolfgang; (2008) Nagios: System And Network Monitoring, 2nd edition - No Starch Press Turnbull, James; (2006) Pro Nagios 2.0 - San Francisco: Apress Josephsen, David; (2007) Building a Monitoring Infrastructure with Nagios - Prentice Hall Dondich,