First connect to the demo system and start a vncserver running
there. If you are already logged in, simply vncserver. Or be
fancy and do this from your desktop: ssh firstname.lastname@example.org
Now setup an encrypted port redirection using ssh from my desktop to
the demo system. VNC uses port 5901 for desktop :1, port 5902 for
desktop :2, etc.
$ ssh -f -C
-L 5901:127.0.0.1:5901 \
-l marc demo.labsystem.net sleep 7200
Now run a vncviewer on the local machine. Be sure to use the command
switches below which give better performance.
$ vncviewer -compresslevel 9 -encodings "tight copyrect" localhost:1
Now have your field person also create a ssh port tunnel (of course
they need an account on the demo system as well) and also run
vncviewer. Now both of you can control the keyboard and mouse for the
system. The performance can be surprisingly good if you have a least
T1 speeds. Across a slower DSL, it is usable, but you feel the delay.