If the server on which PRTG is installed is part of a domain, whereas a few target machines are not, WMI monitoring often fails with the following error “Connection could not be established (80070005: Access Denied …)”. This article lists a few possible steps to resolve this issue, in order to successfully monitor target machines outside your Windows domain.

Basic Steps

• First of all, please check if the correct credentials are used, especially if the hostname is entered in the field “Domain or Computer Name” in PRTG. You can try to use localhost here, especially in the settings of the parent group (if all devices in this group are outside of the domain, of course). Please do not leave this field empty!
• Also verify if any firewalls in between PRTG and the target machine(s) may be interfering with connections on port 135.
• The next thing you should try is to configure the PRTG Probe service to run under a domain administrator account. Sometimes the access rights of the System Account under which the PRTG Probe runs by default are not sufficient. Even though it may sound awkward to use a domain administrator account to query a machine outside of a domain, do try this, as we have actually seen cases where this option got the WMI sensors (for this particular target) to work.
• If the target host(s) are accessible with our WMI Tester tool, but PRTG still insists on showing the 80070005 error, try using "localhost" as "domain or computer name" in the Windows credentials section of the device's settings.

The next options have to be differentiated by the Windows version running on the target machine:

Windows XP/2003

• Head to “Start”->”Run…” and start the registry editor (regedit)
• Navigate to the following key: HKEY_LOCAL_MACHINE\System\CurrentControlSet\Control\LSA\
• Make sure that “ForceGuest” is set to “0”
• Eventually reboot the target machine. It should now be possible to monitor with WMI.
• For further reference please see http://support.microsoft.com/default.aspx?scid=kb;en-us;290403

Windows Vista/2008 (R2)

• Open the control panel, head to the Windows firewall
• Click on “Change Settings” and then please select the “Exceptions” tab
• To enable WMI traffic passing the firewall, select the check box for “Windows Management Instrumentation (WMI)”. Confirm this with Ok.
• Open a command prompt (as administrator) and enter the following line to set another firewall group rule: netsh advfirewall firewall set rule group="windows management instrumentation (wmi)" new enable=yesNote: The name of the group is language dependent and must be translated for non-English Windows versions! So, if you run this command on a German Windows version, you have to replace windows management instrumentation (wmi) by Windows-Verwaltungsinstrumentation (WMI).
• Eventually reboot the target machine. It should now be possible to monitor with WMI.
• For further reference please see: http://msdn.microsoft.com/en-us/library/aa822854(VS.85).aspx
• Add the monitoring user to the Performance Monitor Users group

Windows 7

• Open the control panel, head to “System and Security”, and then click on “Windows Firewall”
• Click on “Advanced Settings” and then, for both Inbound and Outbound Rules, do the following:
• To enable WMI traffic passing the firewall, select all checkboxes for “Windows Management Instrumentation”. Confirm this by closing the windows.
• Open a command prompt (as administrator) and enter the following line to set another firewall group rule: netsh advfirewall firewall set rule group="windows management instrumentation (wmi)" new enable=yes
• Eventually reboot the target machine. It should now be possible to monitor with WMI.
• Add the monitoring user to the Performance Monitor Users group