Use WMI for monitoring auto-discovery on Windows Server

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Published on January 11th 2016 - Listed in Monitoring Windows Icinga


I'm currently working on an internal solution to auto-discover objects to be monitored on a remote Windows server. The goal is to use a web form where the administrator can enter basic information (like IP address) of the remote Windows host and the script auto-detects objects to be monitored; for example services or drives.The script then builds an Icinga2 config which then uses check_nt in the background (NSClient++ installed on the Windows server).

I chose to use WMI for the auto-discovery part. After I successfully compiled and installed the WMI cli (wmic) I was able to launch WMI-SQL/WQL queries on the remote Windows system:

/usr/bin/wmic -U "domain/sa_icinga%passwd" //windowsserver 'select DeviceID from Win32_LogicalDisk where DriveType = 3'
CLASS: Win32_LogicalDisk
DeviceID
C:
D:

However the tricky part was to create a non-administrator user who's able to launch remote WMI calls. Unfortunately the official Windows documentation (Authorize WMI users and set permissions) is somewhat incomplete and simply says:

To perform this task on a remote computer, the account with which you are logged on must be a member of the Administrators group of that computer.

This is actually not true - and I certainly don't want to give administrator privileges to a user just used for monitoring or in this case auto-discovery for objects to be monitored. The simplest way for me turned out to be the following way.

1. Create a new service user in the domain (or as a local user if the Windows server is not part of a domain). In my case this is the "sa_icinga" service account as you see above in the wmic command.

2. Assign this user to the following local groups:

  • Distributed COM Users
  • Performance Log Users
  • Performance Monitor Users

(Start -> Right-Click Computer -> Manage -> Configuration -> Local Users and Groups -> Groups)

3. Modify WMI remote settings in the WMI Control Properties (Start -> Right-Click Computer -> Manage -> Configuration -> Right-Click WMI Control -> Properties).
Switch to the "Security" tab and expand the "Root" object. Select the "CIMV2" element and click on the "Security" button:

Windows WMI CIMV2

Add the service user and select "Enable Account" and "Remote Enable" in the "Allow column:

Windows WMI Security

This was successfully tested on a Windows 2008 R2 Standard server.

Update January 22nd 2016:

It turns out that with this configuration most of the checks and discoveries can be done, however the sa_icinga user was not able to show a full list of Windows services. Only a fraction of the services list was shown.
So once again I tried to figure out how to give the non-administrator user "sa_icinga" the required permissions and found this howto. So far that's the best HowTo I found for this topic. However the solution is to change the security permissions for each service - in reality this is just not possible and I'm not Windows-hardcore enough to pull a PowerShell script or similar out of my pocket.
Another hint I found was on the OP5 Knowledge base, where it says:

When using a non-administrator user it is not possible to monitor all Windows services.
Some services require that some security settings in Windows is modified which is out of scoop for this how-to.

Yap, that's exactly the issue I'm seeing.

So, as frustrating it is, I added the sa_icinga user to the local Administrators group.
However, I disabled Remote Desktop connections for this sa_icinga user. This can be done in Active Directory Users + Computers: Properties of sa_icinga -> Remote Desktop Services Profile -> Deny this user permissions to log on to Remote Desktop Session Host server.
At least this way nobody can abuse this monitoring service account for anonymous logins.


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