Headless YellowDog

[Jim Bauer]

On Saturday 09 October 2004 04:02, Geert Janssens wrote:
>
> I've been following this thread with increasing interest. But as VNC is
> a new area for me, not all is very clear.
>
> I have a server in the basement running Mandrake 10. It also comes with
> a VNC server. Up until now, I always started an X session locally on the
> machine, used the Remote Desktop Connection tool to start a vnc server,
> and then could login from the YDL box on my desk.
>
> Obviously, that's less the practical.
>
> So here are some questions that could further improve my VNC experience:
>
> What is meant exactly with 'servers' in the above quote ? Is this in the
> (for me confusing) context of X where the screen you are working on is
> the server, and the machine being connected to the client ? If so, what
> exactly is meant with the :1, :2 and so on ? Until now, I always used :0
> which I was told to do in a former employment in a unix environment.

Genericaly something is a server if it provides some sort of service.  In X, 
the service that the X server provides is an interface to a monitor, 
keyboard, and mouse.  So your X server running on your computer manages the 
monitor/kdb/mouse and the various programs your run (X clients) use that 
service.

In most cases there is only one X server running on a system.  It is possible, 
but not very common, to have a computer with 2 monitors, 2 keyboards, and 2 
mice that two people can use at once.  When you run a X client program, you 
need to tell it which display to use.  That is specified as 
system:display.screen, where system is the hostname or IP address, and 
display is the display number (starting with 0).  I'll ignore screens for 
now.  Both 'display' and 'screen' can be omitted and you get :0 for example.  
This refers to the first display on the local system.  BTW :0.0 is the same 
as :0 and unix:0 is also the same is :0.   If you set your display to :1 that 
refers to the senond display on that system.

Now bring VNC into the picture.  The VNC server is a X server that doesn't 
manage any monitor/keyboard/mouse.  It just makes it look like it does to any 
X client program that connects to it.  In order to be able to see and control 
anything in that virtual X server you need a VNC viewer program.  The VNC 
viewer connects to a X server (not the vncserver) and displays a window.  It 
also makes a connection to the virtual X server (VNC server).  The VNC server 
tells the VNC viewer what to display in the window it created on the other X 
server.

If you startup vncserver on a system already running another X server (most 
likely on display :0) then vncserver will need to use some other display.  
Unless told otherwise it'll grab the next available one i.e.  :1.


> I understand that I don't need to connect to the local X session on the
> server in the basement, but VNC can start it's own X session. Great!
>
> Next point: I would like to display the VNC session on my YDL box in a
> separate console (or virtual terminal?), like MOL can be run in a
> separate console. I haven't managed that just yet. I only can have a
> window in my existing X session on my YDL box. What magic should be
> performed here ?

Whenever you display a VNC session, you need to run a VNC viewer.  As it is 
another X client, it'll need to talk to a X server.  So you cannot directly 
display the VNC session on another virtual console.  But you can run another 
X server on that virtual console.

This is a slight variation of the multiple monitor/keyboard/mouse previously 
mentioned.  Lets say you already have a X server running (:0) and it is on 
virtual console 7.  You can run another X server on another virtual console.
Run "startx -- :1" (that's 2 dashes). This will startup an new X server (:1) 
on the next available virtual console (8 probably).  Now you can switch 
between the two with ctrl-alt-f7 and ctrl-alt-f8.

Now in your second (:1) X server on vc8 run your vncclient and point it to 
your vncserver running on some other box.  Make it full screen and now you 
can switch back and forth between your regualr desktop and the VNC one by 
using the usual VC switching (ctrl-alt-Fx).

> Also, as I am using the system now, when I open the Remote Desktop
> Connection tool on my YDL box, it starts with the following error message:
>
> "Browsing the network is not possible. You probably did not install SLP
> support correctly"
>
> I have no clue what SLP is all about, and even less of a clue how to
> install it. Any ideas ?

Not me.