Still using VNC or proprietary softwares like Citrix? You might want to check out NX technology. What is NX technology? NX was developed by NoMachine and FreeNX is a GPL implementation of the NX Server. Here is how FreeNX describes the technology:

NoMachine NX is a Terminal Server and remote access solution based on a comprising set of enterprise class open source technologies. Thanks to the outstanding X-Window compression technology developed by NoMachine, NX makes it possible to run any graphical application on any operating system across any network connection at incredible speed. Besides the native X-Window protocol, NX is able to translate and tunnel industry standard protocols like the RDP Protocol, used by Microsoft and Citrix, and the VNC protocol, used by a number of freely available tools, into X-Window, giving secure and fast access to the complete set of network computing facilities available inside a corporate network.

I was going to do a step-by-step installation of the FreeNX server on Debian but Carla Schroder beat me to it. Read her tutorial, then keep reading because I have included a few extra pieces of information:

FreeNX Ups the Remote Linux Desktop Ante
May 31, 2005
By Carla Schroder

Debian Installation
FreeNX has not yet made it into Debian’s official archives. To get FreeNX for your Debian system add this line to /etc/apt/sources.list:

deb http://kanotix.com/files/debian/ ./

Next, run apt-get update as root to update your package lists, then install with

$ apt-get install freenx

It will pull in other packages to satisfy all dependencies, such as expect, freenx, libnxcomp0, libnxcompext0, netcat, nxagent, nxlibs, and nxproxy. During installation it will ask you if you want to use the default DSA key that ships with FreeNX…[I say select the NoMachine keys option]

Then, as root, you’ll need to add users and passwords for users who are authorized to connect to the server. These users must also have system accounts, so if they are not in /etc/passwd you’ll have to create system accounts for them. This is standard SSH behavior, and users who do not have accounts have no business trying to log in, so don’t whine about it. It is also a good security practice to force remote users to have different passwords than their system logins:

$ nxserver –adduser your-username
$ nxserver –passwd your-username

Interestingly, you only get one chance to set the password — it does not ask for confirmation, so type carefully.

It is not necessary to run the nxsetup utility because the installer does the setup for you. Make sure port 22 is open, and you’re done.

To install the FreeNX server under Fedora check out this tutorial by Rick Stout

That takes care of the server side. Now a client application needs to be installed in order to gain access to your shiny new NX server. Go to the NoMachine downloads page and locate the proper client for your OS. Clients exist for Windows, Linux, Mac, and Solaris operating systems. If you are feeling really adventurous you can try the clients for PS2, iPAQ, or Zaurus.

Once you have downloaded and installed the client. Open the program and go through the “NX Connection Wizard”. Fill out the information, and NoMachine will save your settings.
(1) SSL encryption must be enabled. I am not sure why, I don’t have a SSL certificate on my server, but the connection always seems to fail without it. (2) Sometimes when logging on, a message will appear about some error creating a cache. I have gotten it a few times, but I can’t figure out what to do about it. It seems to appear if the client side cache has nothing in it. (If you are having problems with the NX client be sure to clear out its cache) (3) Increase the amount of “memory” cache in the client config settings to 32MB. It just seems to help the performance.