Windows 7 / Networking

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Enabling Remote Desktop and Authorizing Users on a Single Computer

By default, Remote Desktop is not enabled on host computers running Windows 7. To enable Remote Desktop on a single host computer, follow these steps:

1. Click Start, right-click Computer, and then click Properties.
2. Click the Remote Settings link to open the Remote tab of System Properties.
3. Choose either the second or third option under Remote Desktop.

Note Enabling Remote Desktop on a computer requires administrative credentials because inbound rules must be enabled in Windows Firewall to allow the host computer to listen for incoming connection attempts from RDC clients over TCP port 3389. You can change the port that RDC uses by modifying the HKLM\System\CurrentControlSet\Control \TerminalServer\WinStations\RDP-Tcp registry value, but if you do this, you must create and enable an inbound firewall rule on the host computer to allow it to listen for incoming RDP traffic. You also have to configure the RDP client to use the changed port.

The two options for enabling Remote Desktop are:

• Allow Connections From Computers Running Any Version Of Remote Desktop (Less Secure) Choosing this option enables computers running a previous version of Windows to use a version of RDP earlier than 6.0 to connect to the host computer.
• Allow Connections Only From Computers Running Remote Desktop With Network Level Authentication (More Secure) Choosing this option only allows RDP connections from client computers running Windows Vista or later versions. (Computers running Windows XP SP2 or Windows Server 2003 SP1 that have version 6.0 of RDC installed can also connect when this option is selected.)

In previous versions of Windows, Remote Desktop authenticated users late in the connection sequence after the Remote Desktop session had started and Winlogon came up in the session. As a result, Remote Desktop sessions were susceptible to spoofing and man-in-themiddle attacks. With the new Network Level Authentication in RDP 6.0, however, the client and host computers negotiate a mutually authenticated, secure channel for exchanging data using the Security Service Provider Interface (SSPI). In an AD DS environment, by default this mutual authentication is performed using the Kerberos v5 protocol and TLS 1.0.

If you try to establish a Remote Desktop session from a client computer running Windows 7 to a host computer running a version of Windows that supports only a version of RDP earlier than 6.0 warning that the identity of the host computer cannot be verified. When the client computer running Windows connects to the host computer and establishes a Remote Desktop session, the absence of the lock icon indicates that Network Level Authentication has not been used to mutually authenticate the client and host computers.

Note The authentication response displayed while attempting to establish a Remote Desktop session depends on the configuration of the RDC client.

When enabling Remote Desktop on a computer, you must also authorize which users will be allowed to remotely connect to that computer using RDC. By default, only administrators are authorized to remotely connect to the host computer. Authorize additional users by following these steps:

1. Click the Select Users button to open the Remote Desktop Users dialog box.
2. Click Add and then either specify or find user accounts in AD DS (or on the local computer on stand-alone host computers) and add them to the list of Remote Desktop Users authorized to access the host computer using Remote Desktop. This adds the selected users to the Remote Desktop Users local group on the host computer.