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NSCA
NSCA (Nagios Service Check Acceptor) is a utility used to securely send passive check results from remote systems and client hosts to a central Nagios monitoring server. It facilitates distributed monitoring by allowing multiple external systems to report their status centrally, improving scalability and extending Nagios capabilities..
NSCA, or Nagios Service Check Acceptor, is an add-on component designed for the Nagios monitoring framework. It enables distributed monitoring by allowing client systems to send passive check results asynchronously to the central server. Passive checks are generated externally by applications or scripts and transmitted via NSCA to update Nagios on the health status of various hosts and services.
The NSCA daemon listens on port 5667 for incoming messages sent by the nsca_send client utility running on remote hosts. The communication protocol involves a well-defined binary format that contains the host or service information, return code, and status output. While NSCA initially supported plaintext transmission, it has options for encryption to protect sensitive monitoring data during transit. However, this encryption is often considered weak compared to modern standards.
In typical deployments, NSCA is favored for environments with distributed systems or where active polling is impractical due to firewall restrictions or scalability concerns. It complements Nagios by reducing load on the central server and enabling timely updates in complex or segmented network topologies.