SSH and X11 using Cygwin/X

rizhun · 09-21-2006, 11:43 AM

Hello all,

I would like to be able to run X applications remotely from my Windows laptop.
I have been able to do this in the past using eXceed - however, my free trial is running out

So I thought I'd jump in and download and install Cygwin and Cygwin/X.

Now when it comes down to X11 I'm a complete n00b, so I'll just go through exactly what I've done to try and start YaST2 on a remote machine.

Start Cygwin.
Run the command 'startx'.
Used the window this opens to 'ssh -X user@host' (I know you can use other terminal programs but I'm just trying to keep it simple at this stage).
Changed to the root user.
Exported the display 'export DISPLAY=myip:0.0'
Run the 'yast2' command.

Here's where things start to go wrong.

On my session to the remote server, I recieve the following error:

Code:

[root@myserver][/root]$ yast2
Xlib: connection to "172.16.41.62:0.0" refused by server
Xlib: No protocol specified

And on the original Cygwin window I have:

Code:

rizhun@mylaptop ~
$ startx

Welcome to the XWin X Server
Vendor: The Cygwin/X Project
Release: 6.8.99.901-4

Contact: cygwin-xfree@cygwin.com

XWin was started with the following command line:

X :0 -multiwindow -clipboard

_XSERVTransmkdir: Owner of /tmp/.X11-unix should be set to root
winValidateArgs - g_iNumScreens: 1 iMaxConsecutiveScreen: 1
(II) XF86Config is not supported
(II) See http://x.cygwin.com/docs/faq/cygwin-x-faq.html for more information
winDetectSupportedEngines - Windows NT/2000/XP
winDetectSupportedEngines - DirectDraw installed
winDetectSupportedEngines - DirectDraw4 installed
winDetectSupportedEngines - Returning, supported engines 00000007
winSetEngine - Multi Window or Rootless => ShadowGDI
winAdjustVideoModeShadowGDI - Using Windows display depth of 32 bits per pixel
winAllocateFBShadowGDI - Creating DIB with width: 2560 height: 1024 depth: 32
winFinishScreenInitFB - Masks: 00ff0000 0000ff00 000000ff
winInitVisualsShadowGDI - Masks 00ff0000 0000ff00 000000ff BPRGB 8 d 24 bpp 32
null screen fn ReparentWindow
null screen fn RestackWindow
InitQueue - Calling pthread_mutex_init
InitQueue - pthread_mutex_init returned
InitQueue - Calling pthread_cond_init
InitQueue - pthread_cond_init returned
winInitMultiWindowWM - Hello
winMultiWindowXMsgProc - Hello
winInitMultiWindowWM - Calling pthread_mutex_lock ()
winMultiWindowXMsgProc - Calling pthread_mutex_lock ()
MIT-SHM extension disabled due to lack of kernel support
XFree86-Bigfont extension local-client optimization disabled due to lack of shar
ed memory support in the kernel
(--) Setting autorepeat to delay=500, rate=31
(--) winConfigKeyboard - Layout: "00000809" (00000809)
(--) Using preset keyboard for "English (United Kingdom)" (809), type "4"
Rules = "xorg" Model = "pc105" Layout = "gb" Variant = "(null)" Options = "(null)"
The XKEYBOARD keymap compiler (xkbcomp) reports:
> Warning:          Type "ONE_LEVEL" has 1 levels, but <RALT> has 2 symbols
>                   Ignoring extra symbols
Errors from xkbcomp are not fatal to the X server
(--) 3 mouse buttons found
Could not init font path element /usr/X11R6/lib/X11/fonts/CID/, removing from list!
winPointerWarpCursor - Discarding first warp: 1280 512
winInitMultiWindowWM - pthread_mutex_lock () returned.
winProcEstablishConnection - Hello
winInitMultiWindowWM - pthread_mutex_unlock () returned.
winMultiWindowXMsgProc - pthread_mutex_lock () returned.
winInitMultiWindowWM - DISPLAY=127.0.0.1:0.0
winMultiWindowXMsgProc - pthread_mutex_unlock () returned.
winMultiWindowXMsgProc - DISPLAY=127.0.0.1:0.0
cat: /cygdrive/h/.Xauthority: No such file or directory
winInitClipboard ()
winProcEstablishConnection - winInitClipboard returned.
winClipboardProc - Hello
DetectUnicodeSupport - Windows NT/2000/XP
winClipboardProc - DISPLAY=127.0.0.1:0.0
winInitMultiWindowWM - XOpenDisplay () returned and successfully opened the display.
winMultiWindowXMsgProc - XOpenDisplay () returned and successfully opened the display.
winClipboardProc - XOpenDisplay () returned and successfully opened the display.

winProcSetSelectionOwner - Clipboard not yet started, aborting.
winProcSetSelectionOwner - Clipboard not yet started, aborting.
AUDIT: Thu Sep 21 16:58:12 2006: 1656 X: client 6 rejected from IP 172.16.2.111

At first I thought a firewall (one of many at my workplace) might be getting in the way... However If I'm quick enough after running the 'yast2' command I can run at 'netstat -a' from MSDOS on my laptop and see the connection on port 6000 between the laptop and server.

Any help with this would be really appreciated.

Thanks in advance,
riz.

Cyber_Paladin · 09-21-2006, 11:55 AM

The thing with SSH tunneled X session is that you don't have to set DISPLAY. SSH will handle that. In fact if you change that then it breaks.

For me, I use Cygwin on a Windows to do stuff on my Debian box remotely.
Remember to fire up the ssh -X command from an xterm.
Then after you connect if you "echo $DISPLAY" you should see something like "localhost:10.0". That socket is the X socket being tunneled inside the encrypted SSH tunnel.

If you explicity set DISPLAY on the X-client like what you did, you'll run into the X-server authentication problem back in the good old days when all the world's using telnet

So, make sure your shell's startup / logon script does not set the DISPLAY variable.

Have fun

rizhun · 09-22-2006, 08:36 AM

Thanks for the reply Cyber_Paladin, but that doesn't seem to work.

When I echo back $DISPLAY i just get a blank line (ie. its not set).
And when I try and run a command, like 'ikeyman', it doesn't open the window it should.
I just get the error message:

Code:

Error: Can't open display:

Any more ideas??

Cyber_Paladin · 09-22-2006, 01:39 PM

Em... it feels funny if the DISPLAY is not set...

In the SSH server's sshd_config, is the following present?

Code:

X11Forwarding yes
X11DisplayOffset 10

The "10" above can actually be any number.

Another one to try is using a "-Y" instead of "-X'

rizhun · 09-27-2006, 07:38 AM

This turned out to be an 'xhost' problem - although I didn't think it was turned on.
Adding a line to turn 'xhost' on and off again in my .bash_profile fixed the problem.

Hope others find this thread useful.

Thanks for your help Cyber_Paladin.

This thread can be closed!