VNC vs Cygwin

[Longman, Bill]

> On Sunday, May 9, 2004, at 06:18  PM, Greg Hamilton wrote:
> 
> > VNC just sends regular screen grabs to the client so you can see 
> > what's happening on the server console. The client can send 
> mouse and 
> > key stroke information back to the server. Everything you do in the 
> > client is mirrored on the console at the server. This is 
> more than a 
> > little agricultural and very slow. Also, I think VNC servers are 
> > limited to one connection at a time.
> >
> > If you're trying to remotely access a Windows box or Mac OS 
> box it's 
> > great because those operating systems don't allow remote GUI logins 
> > but best avoided if you have the option of an X11 session.
> >
> > Greg
> My experience with VNC does not exhibit these characteristics:
> The server is silent with regard to "Everything you do in the 
> client is 
> mirrored on the console at the server."
> VNC sends pixel updates over the network.  It does not need 
> to be slow 
> - if you have a bandwidth limited network it is good to not do things 
> like have a gradiated desktop background.  Why?  VNC just sends the 
> changed pixels over the network so if  the desktop is updating itself 
> constantly you gobble up a lot of network bandwidth.  I find 
> VNC to be 
> very similar to a dedicated Xterminal,  You are correct in 
> saying that 
> the Xsession itself runs on the server.
> 
> I do not believe that there is a limit on the number of VNC 
> server/client sessions you can run simultaneously

A VNC server acts differently on a Windows box than on a *nix box. On
Windoughs, the server can only provide display for the one display on the
box: the console. On *nix, anyone can start their own VNC server complete
with their own X settings for it; different from their normal, console X
settings on that box. For example, one of the machines on my DMZ is
administered by several groups. They each have their own VNC server runnning
there that allows them to administer their areas. They don't need to install
X server s/w on their desktops, just VNC and they can basically run X, then.

VNC servers can be configured to allow multiple simultaneous users or not,
on both Win & *nix. They can also be configured to spray pixels at different
bit depths and with different encodings and encryptions. The Win server can
be told not to send the  background's bitmap. This is a big help.

Finally, if any of you know of a way to control the console X session
remotely, please let me know. I've certainly been warned time and again
about the bad guys being able to read my X traffic, but I've never yet heard
of anyone taking over my cursor and clicking closed all my windows.

Doug, on your last question you asked about a DCOP error. You'll see this
error when you haven't started KDE. Cygwin's X server cannot provide shared
memory for the MIT_SHM (something like this) X server extension. Nor does it
supply the RENDER extension. Lots of stuff breaks without those and I think
that's why KDE behaves so poorly under Cygwin. I also use Reflection X
(another Win X server) which provides those extensions and KDE works as
hoglike as ever under Reflection but at least it works. I've tried it, it
ran, I exited and ran WindowMaker so I could do something other than
wait....

With your setup, Doug, you might be better off using VNC, if you must use
KDE. You need to make a VNC password with the vncpasswd command, then run
"vncserver :3" to fire up your own X session. Then, on the Win side, connect
to host:3 with VNC and you should be good to go. These directions are pretty
crappy so if you want more details, I can provide them. See the man page for
vncserver and vncviewer.