[svlug] SuSE-9.1 and vnc

[Scott Hess]

On Tue, 28 Sep 2004 12:06:27 -0700 (PDT), Roland Krause
<rokrau at yahoo.com> wrote:
> Who started the vncserver on port 5900, the X-server?

I doubt there is a vncserver on VNC port :0 (TCP port 5900).  I think
there is an X11 server on port :0 (TCP port 6000), which means that
the vncserver can't start another X11 server on port :0.  So you need
to start your vnc server on port :1, which won't conflict with the
existing X11 server.

Hmm.  In the interests of saving an email round-trip, I'll go deeper...

X servers provide a port for clients to connect to them on.  When
local to the machine, these ports are referred to like :0, :1, etc
(remotely you would use hostname:0, hostname:1, etc).  You can only
run a single X server on a given X port (though you could have
multiple X ports mapping to the same X server).

vncserver starts up Xvnc, which is an X server which also listens for
VNC clients on a VNC port.  It uses a similar naming scheme to X for
the VNC ports, and expects the X port to be the same as the VNC port. 
So you can run a VNC server which accepts X clients on X port :1, and
VNC clients on VNC port :1.

So, if you have a standard X server running on your computer's console
(on the monitor, if there is one connected), it will probably be at X
port :0.  If you try to start a VNC server at :0, while VNC port :0 is
open, X port :0 is already in use, so it cannot start up.  You simply
need to use a different port, like :1.  There's no particular
advantage or disadvantage to using :1, or :2, or :17.  You just tell
your VNC client to connect to hostname:17 (or enter 17 in the relevant
field).  I've never seen a VNC client which didn't accept alternate
ports.

To verify this, do something like "ps awwwx | egrep X".  I see a line like:

 3777 ?        SL   143:58 /usr/X11R6/bin/X :0 -auth /var/gdm/:0.Xauth vt7

so there's an X server running on port :0 on my box.

> Actually I want a vncserver running by default so I'd be happy to use
> the one that's started by default.

I don't believe most distributions startup VNC servers by default,
though it's certainly something that you could do.  I think the VNC
distribution includes a sample rc script.  But I think you should
probably get more comfortable with the manual process before embarking
down that road :-).

-scott