To install Nagios on Debian 12, you gain access to an open-source monitoring tool that tracks the status of network hosts, services, and applications. Nagios employs a server/agent architecture, where the Nagios Remote Plugin Executor (NRPE) agent communicates with remote hosts to monitor devices, system resources, and applications. It performs periodic checks on these tracked resources, returns status codes, and generates graphical reports through a web-based monitoring dashboard. This article ......