How do you configure NLA for RDP in Windows Server 2012?

Solution 1:

According to the Windows Server 2012 Group Policy Reference guide:

On Windows Server 2012 and Windows 8, Network Level Authentication is enforced by default.

While the option to enable or disable NLA has been removed from the GUI interface, it's still configurable via the Group Policy setting Require user authentication for remote connections by using Network Level Authentication found at Computer\Policies\Windows Components\Remote Desktop Services\Remote Desktop Session Host\Security. This setting must be applied to the server running the RDSH role.

Solution 2:

It wasn't on for all of our servers. This might be because the server manager had decided to turn it off by default (presumably for the legions of pre-Windows XP SP3 users?!).

As Philippe pointed out - the dialog you want is shown in the Petri article.