What is Remote Desktop?

Remote Desktop is, pretty much, what it sounds like: the ability to access
the desktop of one computer from another. But words don't do it justice, so
let's do some words and pictures and see if we can't make the concept
clearer.

As I type this I'm using my "main" desktop computer. One of the windows open
on my screen is of course the editing program I'm using to write this article.
Another window has a browser, another has a command shell, and so on.

One window has the desktop of another computer within it.

I keep my email on my laptop, but my laptop is in another room. Hence I use
Remote Desktop to access that computer "remotely" from the computer in my
office.

If I close a few of those other windows I'm talking about, here's what it
looks like:

There are a few things to note about that picture:

• The entire image is a snapshot of what's on my office computer.

• The blue menu bar at the very bottom of the image, and the icons on the very
  left, are those of my office computer. (You can see I keep a very clean
  desktop.)

• The window in the middle is a Remote Desktop connection to my laptop in the
  other room.

• The grey menu bar at the bottom of that window, and the icons you can
  partially see on the left side of that window, are those of the laptop.

• The program you see running within that window is my email program,
  Thunderbird, which is running on my laptop.

The bottom line is that using a remote desktop connection I can use my
laptop almost as if I were sitting in front of it, even if it's in
another room.

I'll open up another Remote Desktop connection:

This time I've opened a Remote Desktop connection to a computer not even in
my home. This computer, running Windows 2000, is 10 miles to the south of me at
my wife's place of business. And yet, I can use it almost as if I were sitting
in front of it.

•

Remote Desktop uses a client application that you run on your local
computer. That computer can be almost anything from Windows 98 on up. There's a
Remote Desktop client for the Mac, and it wouldn't surprise me if there were
one for Linux.

Remote Desktop requires that a particular service be running and enabled on
the remote computer. This is either the Remote Desktop service, or "Terminal
Services". Remote Desktop is available on Windows XP Pro, but not Home.
Terminal Services is available on Windows 2000 and 2003 Server.

One important difference between the two: when you access a Windows XP Pro
machine using Remote Desktop the "real" screen and keyboard are switched away
from; meaning that only one person can use the computer at a time. If the
someone logs in at the real console, the Remote Desktop session is closed. If
someone logs in via Remote Desktop, the console session is suspended. In both
cases if the person is logging in with the same account as the active session,
that session is simply "moved" from console to remote, or from remote to
console.

With Terminal Services, more than one remote session can be established
simultaneously, and the console is not affected. Multiple people can use the
same machine at the same time.

•

You enable Remote Desktop on your Windows XP system by right-clicking on
My Computer, clicking on Properties and then
clicking on the Remote tab. Therein is a checkbox
Allow users to connect remotely to this computer. You may also
need to open the incoming Remote Desktop port (3389 by default) in any firewall
you have running on that machine. This is all done on the remote
computer to enable it to be accessed remotely. For example this is what I did
on my laptop.

The remote desktop client is typically already on your Windows XP machine,
in All Programs, Accessories,
Communication. Other versions can be downloaded from Microsoft.

The biggest issue most people face is knowing what to connect to. If you're
connecting to another machine on your local network, you can specify it by name
or by IP address. If you're connecting over the internet, things get a little
more complicated, particularly if the machine you want to connect to is behind
a router.

My favorite solution is to use Hamachi to set up a VPN or Virtual Private
Network so that all the machines "look like" they're on my local LAN, no matter
where they are. Then I can establish a remote desktop connection to the
machines by name or by IP, just as if they really were on my local LAN.

Without using a VPN solution, the following has to happen:

• You would specify the internet IP address of the remote
  machine's router to the Remote Desktop Client. You cannot specify the IP
  address of the machine itself, say a 192.168... address because that is not a
  valid internet IP address, only a local LAN address.

• The router needs to forward port 3389 to the computer you
  want to connect to. Exactly how you perform port forwarding will vary based on
  your router, but this is typically where you specify that local "192.168"
  address, using it to tell the router that this is where you want Remote Desktop
  Connections that come in off the internet to connect to.

Note that by using port forwarding like this, you can specify only one
machine to connect to. It's possible, though somewhat complicated, to set up
different ports in addition to 3389, and have each such port represent a
different computer on your LAN that can be connected to.

Note also that port forwarding is done by specifying the IP address of the
target computer. That means if you use DHCP on that LAN to assign IP addresses,
the address could change, and the forward might need to be reconfigured to use
the newly assigned address. Assigning static addresses on your LAN is one
solution, but well beyond the scope of this article.

By now you can see why a VPN solution such as Hamachi is so lucrative to me.
No port forwarding or router games need be played at all.

Video: here's a video overview I did some time ago that may
also help describe how Remote Desktop can be used:

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