Bug 591664

Summary: Connecting To A System Via VNC Produces A Black Screen Only
Product: [openSUSE] openSUSE 12.2 Reporter: Forgotten User xs3PtXj4XH <forgotten_xs3PtXj4XH>
Component: X.OrgAssignee: E-mail List <xorg-maintainer-bugs>
Status: VERIFIED FIXED QA Contact: E-mail List <xorg-maintainer-bugs>
Severity: Major    
Priority: P3 - Medium CC: forgotten_6yMpDEBP2y, max, milan.zimmermann, richard.wellhouse, s2, sndirsch
Version: Milestone 3   
Target Milestone: ---   
Hardware: PC   
OS: openSUSE 12.2   
Whiteboard:
Found By: --- Services Priority:
Business Priority: Blocker: ---
Marketing QA Status: --- IT Deployment: ---
Attachments: Failed VNC Session

Description Forgotten User xs3PtXj4XH 2010-03-27 16:18:27 UTC
Created attachment 351005 [details]
Failed VNC Session

User-Agent:       Mozilla/5.0 (X11; U; Linux i686; en-GB; rv:1.9.2.0) Gecko/20100115 SUSE/3.6.0-1.2 Firefox/3.6

When running KDE as the default desktop environment, after enabling VNC Remote Administration in YaST and telling the system to open the relevant ports through the firewall on the target machine, a user attempts to start a remote VNC session.  The connection is initiated and a response is received, but only goes as far as producing a black screen with the standard X-server mouse icon (a cross).  The mouse responds to input and moves around the screen area, but no graphics are loaded and no login prompt is presented as it was in previous versions of SuSE.

Reproducible: Always

Steps to Reproduce:
1. Run a standard installation, but de-select automatic configuration.
2. Choose KDE as the default desktop environment.
3. Complete the installation and update the system (currently the system is updated to KDE 4.3.5 during this process)
4. Start YaST
5. Enable Remote Administration, set it to start during boot, and open the required firewall ports.
6. Choose a separate, working machine and start a VNC client (in my case, I tested the KRDC client on openSuSE 11.0 and the TightVNC viewer on WindowsXP with the same results).
7. Attempt to connect to desktop 1 on the remote machine.
Actual Results:  
A black screen with an X mouse cursor appears.  The mouse responds to input, but no graphics are loaded and no login prompt is produced.

Expected Results:  
The KDE login prompt should appear and allow the user to begin a remote desktop session.
Comment 1 Reinhard Max 2010-03-29 07:24:39 UTC
Please try the following:

 1. Edit /etc/xinetd.d/vnc and remove all occurances of the
    "-from localhost" option in the server_args lines.

 2. Restart xinetd (rcxinetd restart)

 3. Try to connet from remote with a VNC viewer.
Comment 2 Forgotten User xs3PtXj4XH 2010-03-31 18:08:20 UTC
There were no instances of "-from localhost" in the file, so I'm going to assume you meant "-query localhost".  I removed those and restarted xinetd as per instructions.  No change I'm afraid.

The only workaround that I know of that works is adding the line:
LISTEN 0.0.0.0
to the bottom of the file /etc/X11/xdm/Xaccess

Adding this and restarting the machine shows the correct login screen as in previous versions of openSuSE.
Comment 3 Reinhard Max 2010-04-01 07:49:26 UTC
I did mean "-from localhost", but had forgotten that this was already removed on 11.2.

Is nscd running on your machine (rcnscd status)?
Comment 4 Forgotten User xs3PtXj4XH 2010-04-06 07:24:57 UTC
The Name Service Caching Daemon is indeed running on the machine.
Comment 5 John Andrew McInnes 2010-04-12 04:59:53 UTC
I experienced this bug also. This fixed it for me (remove IP6 localhost entry in hosts file, Yast->Hostnames):

http://old.nabble.com/Problem-with-OpenSuSE-11.2-and-KDE4-td26505322.html
Comment 6 Forgotten User xs3PtXj4XH 2010-04-12 10:58:24 UTC
Thanks John.  Nice workaround for those of us on IPv4.  Still, it would be nice to have a proper fix so that those on IPv6 can still use their systems.
Comment 7 Forgotten User xs3PtXj4XH 2010-04-15 22:36:56 UTC
Problem does NOT appear to be present in openSuSE 11.3 Milestone 5.  Whatever changes have been made fixed it.  Perhaps someone can look at those changes and figure out what it may have been?
Comment 8 Forgotten User xs3PtXj4XH 2010-05-02 10:12:09 UTC
Unfortunately, the problem is back again in openSuSE 11.3 Milestone 6.  Since this problem doesn't appear to be on track to getting fixed for 11.2, I'm updating it for 11.3 Milestone 6 in the hope that it is solved for the next release.
Comment 9 Milan Zimmermann 2010-07-04 02:42:43 UTC
The same problem still occurs in OpenSuSE 11.3 RC2.
Comment 10 Forgotten User xs3PtXj4XH 2010-07-04 15:54:32 UTC
I have some additional information.  It appears that when the user has selected "Disable IPv6" during install, some IPv6 addresses (such as the loopback address) remain in the hosts file.  Commenting out these lines returns the proper functionality.  Could someone please try to fix these prior to release?  Being able to use remote administration is a pretty major feature... especially given that it has its own Yast2 module.  Naturally, a fix for 11.2 would be nice as well.
Comment 11 Forgotten User xs3PtXj4XH 2010-07-04 15:55:23 UTC
Updated to RC2 as per milan's report.
Comment 12 Forgotten User xs3PtXj4XH 2010-07-04 15:55:48 UTC
Updated to RC2 as per milan's report.
Comment 13 Reinhard Max 2010-07-08 17:12:55 UTC
I've submitted a patch for the Xvnc package today.
It was too late for getting it into 11.3, but I think we'll release it as an update.

You can get the fixed package for testing from the openSUSE build service:
http://download.opensuse.org/repositories/X11:/XOrg/openSUSE_11.3/

Please let me know if it works for you.
Comment 14 Forgotten User xs3PtXj4XH 2010-07-12 07:39:02 UTC
Updating package xorg-x11-Xvnc did the trick.  I have marked this as resolved fixed, but am hoping that the fix will also be backported to openSuSE 11.2, which displays the same behaviour.  

Additionally, this bug: https://bugzilla.novell.com/show_bug.cgi?id=546632 may be resolved, but I have no way of checking it against this fix as I am not able to move my current testing network to IPv6.  Would someone mind checking and closing the bug if possible?

Thanks.
Comment 15 Forgotten User xs3PtXj4XH 2010-07-18 10:20:20 UTC
*** Bug 623254 has been marked as a duplicate of this bug. ***
Comment 16 Richard Wellhouse 2010-08-25 13:47:06 UTC
Trying to find the Xvnc patch mentioned in comment #13, but I do not see it.  Can someone point me to the location of the fix?

Thanks,
Rich
Comment 17 Forgotten User xs3PtXj4XH 2010-08-29 11:39:33 UTC
Well it's been marked as fixed, but has not been delivered to the update repositories yet.  I assume it will be?
Comment 18 Stefan Dirsch 2010-08-29 13:45:03 UTC
(In reply to comment #17)
> Well it's been marked as fixed, but has not been delivered to the update
> repositories yet.  I assume it will be?

Yes.
Comment 19 Milan Zimmermann 2010-10-04 15:12:03 UTC
I can confirm this works in Opensuse 11.3 updated as of October 2010. I am not sure (with) which update it came through, but now setting networking to IPV6, with all the IPV6 giberrish in the hosts file, remote desktop connection works.
Comment 20 Forgotten User xs3PtXj4XH 2012-04-08 11:21:24 UTC
Tested this bug against 12.2 Milestone 2 and the problem has returned. Once again, attempting to log in to the machine via VNC produces a black screen only.
Comment 21 Forgotten User xs3PtXj4XH 2012-04-12 10:21:31 UTC
Fixed platform setting to 12.2
Comment 22 Forgotten User xs3PtXj4XH 2012-04-16 15:23:37 UTC
Bug is still present in 12.2 Milestone 3. Updating.
Comment 23 Forgotten User xs3PtXj4XH 2012-08-06 05:36:05 UTC
I've filed a new bug, as the symptoms appear to have been changed, so I'm not sure if the issue is a duplicate or not. New bug is here:

https://bugzilla.novell.com/show_bug.cgi?id=771745
Comment 24 Forgotten User xs3PtXj4XH 2012-09-10 15:34:56 UTC
This old report is not related to the new one it seems. Closing again.