[SATLUG] Remote Desktop for Linux

Borries Demeler demeler at biochem.uthscsa.edu
Fri Apr 25 06:50:56 CDT 2008


John, thanks for the detailed response! It seems it is worth looking in further
and I'll do this. Just a couple of clarifications below:

> >  2. choice of 8/16/24 bit color
> Not Sure.  Windows client from NoMachine does not seem have that
> option, while the CLI nxdesktop on linux does.

I would expect the server to allow me to set the bitlevel colordepth that
I want to send out to the clients. In a restricted environment, i may go
down to 16 or 8 bit to improve speed.

> >  4. readonly or read/write connectivity is possible (based on password)
> Readonly would infer that you are connecting to existing session.  Not
> sure about this one.

What I mean here is this: In VNC, I can specify two passwords for each
server session. One would allow me to interact with the desktop, and
move the mouse, etc. The other would allow me to see the screen, but
prevent me from messing with it. Say I wanted to show my software to a 
bunch of students at remote terminals, I would have them log in with the 
readonly password so they can see what I do, after I have logged in with
the read/write password. Sometimes I work with my colleague in collaborative
mode where we both have access to the mouse or keyboard. THen both of us
log in with the read/write password. But when I give a presentation I need
to prevent people from advancing slides for me, or grabbing the mouse, etc.

> >  5. OpenGL support
> glxgears in NX seems to work.  Linux client gets ~200fps.  A little
> choppy, but works.  Native on linux client ~2900fps.  On server I get
> ~1700.  Windows client is about the same as Linux client.  It is CPU
> intensive, as the session is not a simple redirect of local screen.  I
> am not a big OpenGL user, so I have not tweaked or tuned for max
> performance.

that seems quite reasonable. I just have mostly static 3D images or
slow openGL animations.

> >  8. speed (VNC seems very fast to me)
> Personal preference.  Compression is adjustable to maximixe B/W available.

Do you get pixellation at higher compression (jpeg compression)? Or is it 
not a lossy compression?

> >  11. automatically drop unresponsive clients
> Not sure.  More details needed.

Sometimes one of the clients may lose a connection or have intermittent 
network issues. Under vnc, the server seems to wait forever so it can push
out the next image to *all* the clients. That makes it hang. This is by the 
way the biggest issue I have with VNC, other than that VNC does everything
very nicely. If I could just prevent the lockups I'd be happy with vnc. But
if there are more stable solutions available, that would be great. Alternatives,
any suggestions on how to deal with the lockups in vnc would be welcome also.

> I do know that the server needn't have xdm or a GUI running for NX to work.

So it starts its own display like vnc? (like, localhost:2)

> Hope that helps.

Yes, very helpful, thanks!

-Borries



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