(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 realizes Nagios monitoring windows host. There are three ways to realize Nagios monitoring windows system: SNMP, nsclient++, nrpe. The latter two ways need to install agent on windows. Because SNMP is enabled on the server at present, this document only introduces the use of SNMP to monitor windows.)