(Nagios is an open source free network monitoring tool with powerful functions and strong flexibility. It can effectively monitor the host status of windows, Linux and UNIX, network settings such as switches and routers, printers, etc. This document mainly implements Nagios to monitor windows hosts. There are three implementation methods for Nagios to monitor Windows systems: SNMP, nsclient++, and nrpe. The latter two methods need to install agents on windows. Since SNMP is enabled on the server, this document only introduces the use of SNMP to monitor windows.)