My IIS looks like this:

Then the question is: How do I enable Forms Authentication on MyWebApp? I mange to change or edit Anonymous Access, Basic, and Windows Auth. However, Forms Auth is not that easy. How do I do this in Powershell?

I’m able to read the setting this way:

(Get-WebConfiguration system.web/authentication 'IIS:\sites\Default Web Site\MyWebApp').Mode

I’m having trouble or no luck with Set-Webconfiguration, or Set-Webconfigurationproperty. I find these cmdlets hard to figure out.

Change happens in web.config, at least the web.config updates when I hit Enable or Disable on Forms Authentication at the IIS manager. Any clues and tips are highly appreciated.

You pipe the authentication configuration settings to Set-Webconfiguration giving the appropriate filter after you modify your properties:

Note: Backup your config before trying this.