Remote Desktop is one of the
most important support tools
for administrators of remote
computers, but it’s often not
enabled on desktop systems
when you need it. If you know
what you’re looking for, however,
it’s fairly easy to enable it
remotely on a network.
The Remote Desktop
service on desktop systems
is always running, even if remote access is disabled.
Whether remote connections
are enabled or disabled is
controlled by a value named
fDenyTSConnections under
the registry key HKEY_LOCAL_
MACHINE\SYSTEM\Current-
ControlSet\Control\Terminal
Server. By default, this value
is 1 (which is disabled). When
you use the Remote tab in the
System Properties dialog box to
enable Remote Desktop access
(shown in Figure 1 for a computer
running Windows Vista),
this value changes to 0.
Because you can enable
remote connections through
the registry, you have a wide
range of options for modifying
Remote Desktop access. Essentially,
any technique for accessing
a registry value will work,
including the following:
- You can open regedit, connect
to the remote computer,
then change the value.
- You can have a PC import a
.reg file on startup.
- You can use Windows Management
Instrumentation’s
(WMI’s) System Registry
provider to make the change
from a script.
- You can use reg.exe to make
the change from
the command
line or a script.
Many
administrators seem to need to enable Remote
Desktop access on the fly. It’s
also usually a good practice to
turn the remote connection
back off when you’re done using
it. So, to simplify the process
of checking whether Remote
Desktop is enabled, enabling it
if it’s not, and disabling it after
you’re done using it, I wrote
three one-line .cmd scripts:
CheckRD.cmd, RDOn.cmd, and
RDOff.cmd.
To check whether a computer
has Remote Desktop
enabled, you can run the
CheckRD.cmd script in Listing
3. To download it and the other scripts, click the Download the Code Here button at the top of this article. CheckRD
.cmd and the other two scripts
take a single command-line
argument: the name of the
remote computer to connect
to. For example, if you want
to use CheckRD.cmd to see
whether Remote Desktop is
enabled on the remote computer
named Client07, you’d
run the command
CheckRD Client07
You can also use this script
to check the setting on the local
system. Just specify a period (.)
as the name of the host computer.
No matter whether you check a local or remote system,
the script returns the value of
fDenyTSConnections. If Remote
Desktop is disabled, 0x1 is
returned. If it’s enabled, 0x0 is
returned.
To enable Remote Desktop,
you can run RDOn.cmd, which
Listing 4 shows. You need to
run this script from an account
that has sufficient privileges to
change the remote machine’s
registry. To enable access on the
Client07 computer, you’d run
the script with the command
RDOn Client07
You’ll be able to immediately
make a remote connection.
If you need to disable
Remote Desktop after you’re
done using it, you can run
RDOff.cmd in Listing 5. For
example, to turn Remote Desktop
off on the Client07 computer,
you’d use the command
RDOff Client07
As you can see, CheckRD
.cmd, RDOn.cmd, and RDOff
.cmd are simple scripts. But
don’t let their simplicity
deceive you. These scripts let
you easily enable and disable a
computer’s remote connection
on demand.
—Alex K.
Angelopoulos
Senior
Network Engineer