Success was Re: VNC Server setup on Linux

Joel Sherrill joel.sherrill "at"
Thu, 17 Jan 2002 22:10:43 +0000

David Colliver wrote:
> > David Colliver wrote:
> > >
> > > I would add that using the method on my site, there is more potential to
> > > lose work. Clicking the X of your window will close VNC. No questions.
> Also,
> > > if your machine goes to sleep, you will lose it, same as if your network
> > > fails.
> >
> > But this is the same as when using an Xterminal.
> >
> > It might also be worth mentioning that if you are running a number of
> > sessions, the difference between 8 and 24 bit color depth is noticeable
> > on the CPU load.  I pop'ed up a single VNC client session with a
> > terminal
> > and then continuously cat'ed /etc/termcap while running top on the
> > console.
> > On a 1 Ghz machine, there was approximately 20% difference in CPU load.
> > I would guess that for most users 8 bit depth is more than sufficient
> > and seems to place less strain on the host and network.
> >
> I am running 16bit colour. I had a serious problem though, seems to me like
> VNC is a very high priority within windows. I left mine running all day
> yesterday, then overnight. During yesterday, I lost 15 minutes on my local
> clock. Overnight, I lost another 45.
> I am using KDE. I had the Matrix screensaver on. It seems that this
> screensaver will take many local clock ticks away from me, even though the
> viewer was in the background. I also seriously noticed my sound breaking up
> locally.
> My local machine is a Dell Inspiron 8000, PIII 750 running ME. My linux
> machine is a P150  with 96MB memory.
> Would this be normal? Is it possible for future versions to be less hungry
> when not in focus?

I don't know on this one but for sure the screen saver is going to
bandwidth.  I could see blips when someone ran a digital clock with

> > > What I would like to know now is, is there a button or something I can
> press
> > > that will save everything, like when I press the logout on my KDE panel,
> but
> > > without logging out. Is there also a way to signal to Linux that I am
> > > closing the remote session?
> >
> > That would be a nice thing to know about or have.
> >
> I suppose there could be some hacks out there that can read the source and
> come up with something.

I have enough development with RTEMS to keep me happy so I will leave
one alone. :)
> > > If someone can explain the gdmconfig on port 177 as mentioned below, I
> will
> > > happily put that up in my instructions. Unfortunately, with my limited
> linux
> > > knowledge, I don't understand a word he said.
> >
> > gdmconfig is a nice GUI utility.  Run it.  There is a pane on the
> > left hand side labeled "Options."  Select "Expert mode".  This
> > shows a number of tabs.  Select "XDMCP".  There is a fairly
> > obvious checkbox at this point that says "Enable XDMCP".
> That'll be why I don't know anything about it. I can't get Gnome running on
> my machine for some reason. I will try and paraphrase that for the page.
> Would something like:
> If running Gnome as your desktop, start gdmconfig, select Expert Mode,
> ensure that Enable XDMCP is checked. (You must be logged in as root)
> Is root the correct login though?

This sounds sufficient.  You need to be root but if you are not,
gdmconfig will ask you for the root password.  You have to be
root to do the rest of the steps so this is consistent.

> > Also my standard test of "telnet localhost portnumber" does not
> > seem to work for 177 even though it is enabled.  This is probably
> > a UDP/TCP issue but that test was bogus.  VNC/XDM works now and
> > I still can't telnet to that port.
> >
> When I said to check the port by telnetting to it, I meant the VNC port, not
> the 177.

OK.  Well 5950 worked. :)

> > > Regards.
> > > Dave.
> > >
> > > p.s. The site ( where the instructions are is
> being
> > > moved to another server within the next few days. If you cannot get
> access,
> > > then try again a little while later.
> >
> > As long as it doesn't go away entirely I am happy. :)
> It won't go away for a while, though I will still like articles for the site
> if anyone is up to it. Mainly programming articles, but configuration
> articles like this are also welcome. I can't do all the articles by myself.
> My strengths are in VBScript and stuff.

I am the maintainer of the free real-time OS RTEMS so I tend to focus
on that and related things (GCC Steering Committee, building cross
development RPMs, etc).  I am always happy to add to instructions 
like these because it is really important to have clear documentation.
Your write-up is certainly that. 

> Regards.
> Dave.
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Joel Sherrill, Ph.D.             Director of Research & Development
joel "at"                 On-Line Applications Research
Ask me about RTEMS: a free RTOS  Huntsville AL 35805
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