Nagios and Icinga passive monitoring agents

Source: EarwickerFollowing is a list of passive monitoring agents for Nagios and Icinga that I have collected over the internet:


NCPA is a relatively new passive monitoring agent.

  • Available for Linux (RPM and Deb packages available), Windows and MacOS.
  • Has a web based admin page
  • Communicates over HTTP protocol.
  • Supports both passive and active checks (see here how to execute active checks)


An improved version of NSCA. ncsa-ng is a server application, accepting health checks from the agents, and submitting them to Nagios.

See examples in Icinga’s web site.

send_nsca is the agent which is installed on the hosts to be monitored. send_ncsa sends the healthchecks to nsca-ng server.

  • Supports encrypted communications between the agent and server using TLS
  • Written in C
  • Supports submitting both health checks and commands such as service issue acknowledgement to Nagios.
  • Can allow only health checks commands to be submitted.


A passive check agent for sending healtchchecks over HTTP protocol. NSCAweb project is hosted in GitHub and is actively developed and updated.

Note that NSCAweb does not run passive checks automatically – there should be another process or cron job that runs the passive checks and submits their results to NSCAweb.

  • Supports buffering of messages to Nagios server in case of a network issue
  • Supports SSL encryption of the communications
  • Communicates over HTTP protocol
  • Sends healthchecks to destinations: another NSCAweb server, Nagios command file (nagios.cmd), NRDP or a file.
  • Load balances or failover between multiple URLs of destination
  • Can send to multiple destinations
  • Written in Python


NSCA is the original Nagios passive checks agent. Its code was last updated in 2012.

Configuration example in Icinga’s web site.

  • An NSCA instance needs to be installed on the Nagios server. It acts as a server accepting health checks results from the monitored hosts, and submits them to the Nagios external command file.
  • On the monitored hosts, NSCA is installed and configured as agent, sending the health checks to the NSCA instance which is installed in the Nagios server.

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