Dear All,
I think I now have a clearer approach to finding solutions to some of my
problems. the suggestions of Stephen, Troy and Miles were particularly helpful.
First, the the solutions obtained so far:
enabling Xforwarding and restarting daemons (e.g., sshd) permits me to have
trouble-free displays over ssh or from xterm windows of different users on the
same console.
From the help offered, I think my solution strategy for multi-terminal display
could be one of the following:
1) Bring up vnc display, have a "master vnc viewer" that can read/write on the display,
and let all the other vnc viewers be "slave vnc viewers" that can only view the display.
Unfortunately, blocking keyboard/mouse actions using the options menu from pressing the F8 key can
be reset by the user. An suggestions to configure vnc to have such master-slave viewers?
2) Create a separate account, which can possibly become insecure by granting
xauth authorities, and use vnc to display whatever. While the implications of
extending access (via xauth) frighten, the use of a video conferencing tool,
such as EVO, seem to require internet access, whereas the machines I'll use are
in a closed LAN. Does anyone know of a video conferencing tool that does not
register to/through the internet?
Once more thank you all for the support.
William.
--- On Tue, 5/5/09, Stephen J. Gowdy <[email protected]> wrote:
From: Stephen J. Gowdy <[email protected]>
Subject: Re: Problems using X Windows Display
To: "William Shu" <[email protected]>
Cc: "Miles O'Neal" <[email protected]>, [email protected]
Date: Tuesday, May 5, 2009, 7:44 AM
On Mon, 4 May 2009, William Shu wrote:
Thank you very much Miles!
I rebooted both machines and I can now view pdf/ *.ps files without
complaints!
vncviewer now opens on the host machine when invoked from the remote
machine through ssh. However, I have the following three problems (whose
solutions I guess will help end this thread):
1) Everything has suddenly become so slow on the host machine (I think);
shortly after opening the vnc window seems to freeze, not displaying X clients,
though the window itself can be reduced or expanded!
Sorry, no idea there.
2) Trying to open vnc without ssh complains of no route to host (error
113). Also, xclock complains of inability to open display.
This is probably your firewall preventing access as I mentinoed. Looking at it
I think you need to open 5901 on your server. I've never used though so
I'm not sure.
3) Related to (2) above, it seems I can only project X disply on another
terminal through ssh, which requires login (and hence knowing another user's
password). Is there no other secure way of doing this, where the target user can
selectively authorise the display?
Each user could have an account on the host machine that is different.
They'd all need to know the shared password for the VNC server though.
Probably not a good idea.
You can use xauth as described before to allow a user to do everything with
your X session either via an ssh tunnel or directly if you open port 6000
(assuming your display is :0) on your firewall. However, something like EVO
would be a much safer way to share a desktop window. There are probably other
applications that would do it too.
The following outputs show what transpired:
[...@hpsl5 ~]$ ssh -XY [email protected]
[email protected]'s password:
Last login: Tue May 5 02:57:19 2009
[...@inteksl52 ~]$ echo $DISPLAY
localhost:10.0
[1]+ Done evince
Desktop/semanticKnowledge-a4-geissler.pdf
[...@inteksl52 ~]$ vncviewer &
[1] 6612
[...@inteksl52 ~]$
VNC Viewer Free Edition 4.1.2 for X - built Feb 11 2009 12:55:24
Copyright (C) 2002-2005 RealVNC Ltd.
See http://www.realvnc.com for information on VNC.
Tue May 5 03:08:35 2009
CConn: connected to host localhost port 5901
CConnection: Server supports RFB protocol version 3.8
CConnection: Using RFB protocol version 3.8
Tue May 5 03:08:54 2009
TXImage: Using default colormap and visual, TrueColor, depth 24.
CConn: Using pixel format depth 6 (8bpp) rgb222
CConn: Using ZRLE encoding
Tue May 5 03:18:27 2009
main: End of stream
[1]+ Done vncviewer
[...@inteksl52 ~]$
<... snip ...>
[...@hpsl5 ~]$ vncviewer 192.168.10.20:1 &
[1] 3888
[...@hpsl5 ~]$
VNC Viewer Free Edition 4.1.2 for X - built Feb 11 2009 12:55:24
Copyright (C) 2002-2005 RealVNC Ltd.
See http://www.realvnc.com for information on VNC.
Tue May 5 03:38:32 2009
main: unable to connect to host: No route to host (113)
[1]+ Exit 1 vncviewer 192.168.10.20:1
[...@hpsl5 ~]$
[...@hpsl5 ~]$ xclock -display 192.168.10.20:1 &
[1] 5564
[...@hpsl5 ~]$ Error: Can't open display: 192.168.10.20:1
--- On Tue, 5/5/09, Miles O'Neal <[email protected]> wrote:
From: Miles O'Neal <[email protected]>
Subject: Re: Problems using X Windows Display
To: [email protected]
Date: Tuesday, May 5, 2009, 1:02 AM
William Shu said...
|Xforwarding:
|------------
|Changed the Xforwarding to yes in /etc/ssh/sshd_config of remote mach=
|ine (inteksl52):
|
|#X11Forwarding no
|X11Forwarding yes
Did you restart the ssh daemon after that change?
-- /------------------------------------+-------------------------\
|Stephen J. Gowdy | CERN Office: 8-1-11|
|http://cern.ch/gowdy/ | CH-1211 Geneva 23 |
| | Switzerland |
|EMail: [email protected] | Tel: +41 76 487 2215 |
\------------------------------------+-------------------------/
