check_mk

Check_mk adopts a new a approach for collecting data from operating systems and network components. It obsoletes NRPE, check_by_ssh, NSClient and check_snmp. It has many benefits, the most important of which are:

* Significant reduction of CPU usage on the Nagios host.
* Automatic inventory of items to be checked on hosts.

http://mathias-kettner.de/check_mk.html