The NoMachine X protocol extension is *NOT* proprietary. On the contrary. It is GPL'd. NX is available in source code and the license is GPL.

What probably confused you was the fact that NoMachine (the company) also offer a proprietary, commercial product (but it is dead-cheap if you ask me) built on top of the very same GPL'd source code library.

The GPL'd version works from the command line. However, you need to be quite a bit of knowlegeable to make it work correctly.

The commercial product is very easy to set up. You can be up and running within 5 minutes.

The GPL'd and the commercial NX use exactly the same library (unlike for example WINE and CodeWeaver's CrossOver). The GPL'd NX has the same performance boost as the commercial product.

KDE is currently working to include NX technology in its next major release of the desktop....

Thank you, fixed.