vncserver configuration ?

[Boggess Rod]

>I have an Ubuntu machine that lives behiind a NAT'es firewall. Various
>users, who have access to Windows machines only, need to be able to
access
>this machine,  and log on to it to various accounts.
>
>What I have in mind is setting up VNC on this machine, such that when
you
>connect, you are presented with a login banner, much like you would get
>with XDM.
>
>I can't seem to find any inormation as to how to set this up. Most of
the
>resources that I am finding talk about setting VNC up so that it
presnes
>the desktop of an already loged in user. It would be good if this VC
>session could support muliple idnependent sesions also.
>
>Sugestions?
>
>--
>A: Because it messes up the order in which people normally read text.
>Q: Why is top-posting such a bad thing?
>A: Top-posting.
>Q: What is the most annoying thing in e-mail?
>
>------------------------------

Have you looked at xrdp? I haven't tried this with a Network Address
Translation (NAT) Firewall, but I don't know how this would differ. In
particular, I've had to access Microsoft Terminal Services Client
(Remote Desktop) through the same, and the setup should be similar. The
NAT is the problem, really, trying to figure out who gets forwarded and
who goes splat on the firewall. (XRDP is supposed to support multiple
sessions, too.) I mention this first and foremost because it shouldn't
require your Windows users to install anything complicated -- just fire
up Remote Desktop, which is already installed with their OS.

I hear also that there's a beta release of LogMeIn for Linux, if that
suites your needs more. It bypasses the firewall by using a third-party
rendezvous point (if configuration of port forwarding on the NAT is the
problem). I'm afraid this works like VNC, though, in that you get the
active console (not necessarily with someone logged on, but there is
only one shared session). 

Alternatively, I understand that xrdp is based on VNC, and since it's
public, you might look at their source or contact the developers to see
if they can help you fiddle with VNC to make it do what you want.