xdmcp

[Gavin McCullagh]

On Fri, 01 Dec 2006, Pan, Richard wrote:

> Is anyone running their edubuntu server as an XDMPC server?  I've been 
> testing it out at my school.  It seems like an interesting way to deliver 
> linux specific applications to users while retaining the mac os and 
> windows os at my school.  Does anyone have any feedback on doing this?

Edubuntu uses something quite similar to XDMCP for its thin clients.
People have used XDMCP for quite a long time for thin clients.  However,
one of the drawbacks of it is that all mouse-clicks, keystrokes and window
images get sent in the clear across the network.  This means someone can
snoop them.  

Instead edubuntu uses a tunnelled ssh session.  ldm (a display manager)
runs on the thin client, you type your username to it and it starts an X
server and initiates an ssh connection to the server running an xsession
displayed locally.  This means all network traffic is encrypted.  There is
a cpu cost in the encryption but it's not too high as a cheap but
relatively secure cypher has been carefully chosen for ldm.

I'm not sure how hard porting ldm to windows would be.  It's python so it
should be feasible -- particularly in cygwin.

If you are not concerned about the security, I've used XDMCP and it works well.

Another alternative might be NX, which is available freely, you can get a
client for windows and it usually runs over ssh.  NX is mainly created to
run over very limited bandwidth (eg a DSL server from home).

	http://www.nomachine.com/

Gavin