Check_MK, OMD and Nagios

Welcome to the official homepage of Check_MK - a new general purpose Nagios-plugin for retrieving data.

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.

The larger your Nagios installation is, the more important get these points. In fact check_mk enables you to implement a monitoring environment exceeding 20.000 checks/min on the first hand.

Availability and Support

Check_mk is free software. You can use, modify and redistribute it under the terms of the GNU GPL Version 2. Professional support for check_mk is available from us. Please contact us, if you need improvements or general help with setting up Nagios and check_mk.

Basic principle

The following figure illustrates how check_mk works. Data is retrieved in four steps:

1. For each host Nagios triggers one active check per check interval. This active check calls check_mk as plugin.
2. check_mk connects to the target host via TCP. An the host the check_mk_agent retrieves all relevant data about that host at once and sends it back as ASCII text.
3. check_mk extracts performanca data and directly insert that into round robin databases.
4. check_mk extracts relevant data, compares it against warning/critical levels and submits all check results of this host via Nagios' passive service checks.