About WMI Monitoring
This page reviews how to use WMI agentless plugins which is valid for use with any version of GroundWork Monitor. Further, those customers using the GroundWork Distributed Monitor Agent (GDMA) may find the description of plugins and troubleshooting section in this document useful.
WMI Agentless Plugins Project
Windows Management Instrumentation (WMI) is a management standard technology for accessing management information and automating administrative tasks in an enterprise environment. There are two main systems management architectures; Agent-based where the proprietary software agent is loaded on a managed system and, Agent-less which depends on management functionality that is built into a managed system.
This project consists of a collection of script monitors (.vbs for starters) that use the Microsoft .NET Framework and WMI to retrieve performance data from remote Windows hosts without the need for agents on the remote hosts. Initially we have about 20 scripts, although it is a fairly minor matter to script others.
There are large numbers of WMI Classes on Windows hosts. This plugin package with a small change to each plugin can be used to retrieve almost any parameter of interest in the default WMI namespace. There is no need for agents on the remote hosts.
The plugin package comes with an NRPE configuration file that can be included from the base nrpe.cfg file. Some of the plugins retrieve specific properties such as CPU load percentage, disk utilization, disk and network I/O, etc., while others are for retrieving arbitrary properties from WMI. The provided NRPE configuration file defines NRPE commands using the plugins to get both specific and arbitrary properties and there are documented syntax examples for each command.
Plugins are configured to return performance data where it makes sense which facilitates easy graphing of results on a Nagios server.
A typical monitor works like this:
This script returns a string to stand out that says something like:
The warning and critical thresholds will be passed as command line arguments (in percent).
In addition it returns an exit value like this:
All scripts return syntax and help if passed the --help command line option. And all scripts return performance data formatted according to the Nagios Plugin Development Guidelines.
Description of Plugins
The following table lists and describes plugins in the package.
checks WMI counters of type 'PERF_100NSEC_TIMER'
checks WMI counters of type 'PERF_COUNTER_BULK_COUNT'
checks WMI counters of type 'PERF_COUNTER_COUNTER'
checks WMI counters of type 'PERF_COUNTER_LARGE_RAWCOUNT'
checks WMI counters of type 'PERF_COUNTER_RAWCOUNT'
checks load percentage of one or more CPUs
checks disk I/O of one or more logical disks
checks disk usage of one or more logical disks
checks RAM, page file, or total memory usage
checks network I/O of one or more TCP/IP network interfaces
checks number of running processes matching a search expression
checks WMI counters of type 'PERF_RAW_FRACTION'
checks the state of an installed service
enumerates information about processors, installed services, running processes, network interfaces, and logical disks for use in configuring other plugins
enumerates information about WMI classes and properties to determine which counter plugin to use
checks system uptime and enumerations information about the hardware and OS
checks OS version to verify WMI is working
- NRPE_NT version 0.8b: The remainder of this document assumes that NRPE_NT has been installed under C:\NRPE_NT with the executable and configuration file under C:\NRPE_NT\bin. It also assumes that you have tested correct operation of NRPE_NT by calling it with the check_nrpe Nagios plugin from your Nagios server. Version 0.8b is necessary in order to fully support specification of some special characters when calling NRPE_NT from check_nrpe. NRPE_NT can be downloaded from Sourceforge.
- Nagios: Nagios 2.x or later with check_nrpe plugin compatible with NRPE_NT version 0.8b. Nagios can be found at www.nagios.org.
- Downloads: See the WMI section in the Downloads page for plugins and scripts.
Once you have installed NRPE_NT on a host (designated as <
host>) and tested that it can be called from your Nagios server with check_nrpe -H <host> create the following directories:
Copy all of the VBS programs from this directory into:
Copy the file V2_nrpe_commands.cfg into:
Edit C:\NRPE_NT\bin\nrpe.cfg and append the following line to the bottom:
- Restart the NRPE_NT service.
After completing the installation procedure you should be able to call each of the installed scripts with the commands defined in V2_nrpe_commands.cfg either from the Windows server itself or from the Nagios server using check_nrpe.
On the Windows server you installed NRPE_NT and the plugins on, open a command window and type:
The output you get should look something like:
This indicates that the plugin was able to successfully talk with the WMI service on 127.0.0.1 and retrieve the OS version.
On the Nagios server, type the following command in a shell once you have changed directory to the location of the check_nrpe plugin:
The output you get should look something like:
You have just executed the same verify_wmi_status.vbs plugin but through the NRPE_NT service from your Nagios server.
The following example Nagios command and service definitions assume you have Nagios 2.x or later installed with a version of check_nrpe compatible with NRPE_NT v0.8b. They also assume that $USER1$ points to the directory containing check_nrpe, and $USER21$ is the address of the host on which NRPE_NT is installed! Download information about both Nagios 2.x (or later) and NRPE_NT v0.8b is available in the install document referenced above.
For a list of further examples refer to the NRPE_NT configuration file in the download reference above. One key point is that you can reverse warning and critical thresholds and have match in the reverse sense, (e.g., If you set
-w 80 -c 50 and the returned value is
90 the return code will be
NRPE Log Files
You can use Notepad or Wordpad to open the NRPE log file located on your monitored server at Local Disk (C:) > NRPE_NT > bin > nrpe_nt.log. Each time the agent is asked to do something you will find a line in this file. At service start up the configuration files are read and if there are issues you may see some complaints, and further down the file is a read out on the commands sent to the agent from GroundWork.
If you are receiving timeout errors you may need to check your NRPE Windows machines firewall settings to see if there is access to the 5666 port. The steps below review how to create an Inbound Rule for this port.
- Navigate to advanced security from your NRPE Windows machine, (e.g., Start > Administrative Tools > Windows Firewall with Advanced Security).
- Add a rule that allows inbound access on this machine using port 5666:
- Select Inbound Rules, and click New Rule.
- For Rule Type, select Port, click Next >.
- For Protocols and Ports, select TCP and Specific local ports entering 5666, click Next >.
- For Action, select Allow the connection, click Next >.
- For Profile, check each that apply to your environment, click Next >.
- For Name, enter a name and description for the NRPE rule (e.g., NRPE), click Finish.
- You should see the rule listed at the top, if you scroll to the right you will see it is set for Port 5666.
- Start the service.
- Select Start > Windows Administrative Tools > Services.
- Locate Nagios Remote Plugin Executor in the list, and click Start the service.
WMI is installed on newer versions of Windows and can also be downloaded and installed on Windows NT. However, sometimes there are issues in getting WMI functioning. Most often these are easy to solve by ensuring authentication is set up correctly but in other cases there are corrupt or missing data structures on the remote host. There are a number of references on the Internet to assist with troubleshooting WMI problems. The plugins in this package assist with this troubleshooting by returning the WMI error code and (if possible) a description for that error.
If you are using the plugins without supplying -user and -pass arguments then the NRPE_NT service must be run as a user with administrative privileges on the host that the plugins are targeting. If you are using the plugins with -user and -pass arguments then that user must have administrative privileges on the target host.
In the case where you're not using the -user and -pass arguments the use of a domain administrator account and then making sure that domain administrators have local administrative rights on each target host is the most efficient and maintainable solution. Another method involves defining a local account on each target host that uses the same account name and password as that passed to the plugin or as that being used to run the NRPE_NT service.
We list the following URLs on WMI and WMI troubleshooting for your convenience and will make every attempt to keep the links up to date:
- WMI Classes: A list of Microsoft WMI classes and their properties. Note that other vendors extend the WMI schema with their own classes, e.g. Cisco AVVID products.
- Using WMI to monitor performance: A reference from Microsoft.
- Repairing WMI: A reference from Microsoft.
- WMI Tools: WMI Browsing Tools
- WMI Diagnosis Utility: Microsoft's WMIDiag Tool to troubleshoot the state of WMI on a computer.