You can execute code when a service or host changes state.  These are called event handlers.

  1. Go to the Windows server and create a local user
  2. Create the following script called iisreset.sh in your Nagios plugins directory replacing the username and password in the three locations below 
    #!/bin/sh
    #
    # Event handler script for restarting IIS on windows server
    #    Requires a local user on the server with the username and password below

    if [ $# -eq 3 ]
    then
            if [ "$1" = "CRITICAL" ]
            then
                    if [ "$2" = "HARD" ]
                    then
                            # Start the service
                            /usr/bin/net rpc service stop W3SVC -I $3 -U User%password >/dev/null
                            sleep 4
                            /usr/bin/net rpc service start W3SVC -I $3 -U User%password >/dev/null 2>&1
                            sleep 4
                            /usr/bin/net rpc service status W3SVC -I $3 -U User%password | grep 'W3SVC'
                            exit 0
                    fi
            fi
    else
            echo "Invalid number of arguments"
            exit 1
    fi

  3. Edit your commands.cfg file in the Nagios configuration directory 
    define command {
            command_name    iisreset
            command_line    $USER1$/iisreset.sh $SERVICESTATE$ $SERVICESTATETYPE$ $HOSTADDRESS$
            }

  4. Add the event handler command to an existing service definition 
    define service{
                    host_name                         somehost
                    service_description        HTTP
                    event_handler                  iisreset
                    ...
                    }


  5. The script will be called like this.  You can put this in a command line to confirm it will work. /usr/lib/nagios/plugins/iisreset.sh CRITICAL HARD 10.10.0.2
  6. Reload or start Nagios
    /etc/init.d/nagios3 reload