PowerShell for Windows Admins

Sep 26 2017   10:04AM GMT


Richard Siddaway Richard Siddaway Profile: Richard Siddaway


I still see a lot of people using the WMI cmdlets – Get-WmiObject etc. You really should be using CIM nit WMI. In other words use Get-CimInstance rather than get-WmiObject etc etc.

Why do I say that?

Two main reasons.

Firstly, the WMI cmdlets are effectively deprecated. Any further development effort will be for the CIM cmdlets.

Secondly, and to my mind more important, is that the CIM cmdlets use WS-MAN for access to remote machines. If you have PowerShell remoting enabled you have access to the machine via a CIM session – either ephemeral using the cmdlet name or persistent using a CIM session.

The WMI cmdlets use DCOM for remoting which is blocked by default on the Windows firewall and most other firewalls and routers giving the RPC server is unavailable error.

The only time there is justification for using the WMI cmdlets is if you’re on a machine that has Powershell v2 installed and if that’s the case why haven’t you upgraded? If you can’t does that mean you’re running an application (usually Exchange or System Center) that doesn’t allow you to upgrade PowerShell.

Maybe its time to perform that upgrade.

As another thought PowerShell v6 includes the CIM cmdlets but not the WMI cmdlets!

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