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Old 11-27-2004, 07:32 PM   #1
akidd
LQ Newbie
 
Registered: Jan 2003
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gdm, vnc and XDMCP stopped working


I've used VNC to access my local LAN machines from one PC. It has worked exactly like Gentoo Wiki HOWTO Xvnc terminal server forever, but an emerge update ago or so it stopped working and I can't figure out why.

So what happens: on a machine (not the one with with the problem) I invoke vncviewer <URL_remote_machine_with_problem> I get the remote gdm login in the correct color depth and geometry for the machine with the problem, I can type in credentials in gdm or kdm but then afterwards only a blank window and the mouse cursor. KDE never loads as it used to...

I have gone back through and verified every step in every config file as in the howto, but it still doesn't work. I've checked permissions on all the files I know about, installed and uninstalled almost every involved component, googled for hours following threads that seemed similiar but ultimately weren't helpful

Starting GDM/KDM and KDE on the machine with the problem works exactly like it always has locally...

Even if you dont' know Gentoo - any ideas, suggestions, tips... I've spent so much time on this problem...

Thanks.

Last edited by akidd; 11-27-2004 at 07:34 PM.
 
Old 11-28-2004, 10:20 AM   #2
hob
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You probably ought to have just one display manager installed and stick with it - GDM (if you mainly use GNOME), or KDM (if you mainly use KDE). I doubt that has anything to do with the problem, but it will keep things simpler.

The display manager launches whatever "session" you selected. It sounds like the display manager is working absolutely fine, but there is a problem starting up KDE remotely. This can be tested by loading KDE with VNC without using the login screen, xinetd etc...

From memory:

- create a new test account.
- log in with the test account.
- at the command-line: vncpasswd. This sets the access password for the VNC session.
- Edit the file /home/testaccount/.vnc/startx to read:

start-kde &

So that it loads KDE rather than TWM. I *think* that this is correct, but I haven't used KDE in a while.

- type vncserver. It will tell you the display number.

This loads a copy of VNC that will launch KDE. If successful servername:displaynumber in VNC viewer and type the VNC password you set with vncpasswd.

If it fails you can look at the log in /home/testaccount/.vnc to see where the error is occurring.

You can use VNC to connect to another display on the same system - this eliminates the possibility of network problems getting in the way.
 
Old 11-28-2004, 12:58 PM   #3
akidd
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Thanks Hob for the response... I haven't had one despite weeks of working this issue. I know it would work if I reinstall everything - but Gentoo makes this a bit too much work to consider lightly.

So I tried what you said to no avail. Plus I tried just changing my wm to TWM and the same thing happens. I can login and then a blank screen with a mouse cursor.

very frustrating.
 
Old 11-28-2004, 04:04 PM   #4
hob
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I didn't think it would work as such... I was really hoping that you could get something from the VNC log files.

To confirm whether twm works, you should try adding xterm & to the startx file, so that VNC loads twm and then a terminal window.

I had an issue like this with Mandrake and TightVNC. The problem there was that TightVNC didn't support a feature of X that GNOME relied on, so twm would work and GNOME would fail (but the errors were captured in the log file). I later moved to Fedora Core, which uses the mainline RealVNC rather than TightVNC, and that worked correctly.

It's probably worth trying RealVNC 4 instead of TightVNC.

Last edited by hob; 11-28-2004 at 04:08 PM.
 
Old 11-28-2004, 07:13 PM   #5
akidd
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I removed tightvnc and tried realvnc - same exact results. So I guess vnc is out of the list of suspects.

I also tried switching to twm in Xsession to see if something was logged as you suggest. The log isn't in /var/log - where is it? The same exact problem happens with twm as wm though...

Any further suggestions?
 
Old 11-29-2004, 05:31 AM   #6
hob
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If you use "vncserver" to launch a session the log file goes in /home/user/.vnc

I'm assuming that you are getting the grey stippled background (which is X before the window manager is layered on top). Is that right, or are are you seeing something else ?
 
Old 11-29-2004, 04:13 PM   #7
akidd
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Registered: Jan 2003
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no I get the gdm/kdm login screen and can type in my credentials - but after I click the login button nothing happens.
 
Old 11-30-2004, 05:15 AM   #8
hob
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If you use the vncserver command to manually load a VNC display GDM/KDM doesn't come into play, and the desktop specified in /home/test/user/.vnc/startx should load straight up, or the VNC session should crash and log the errors in /home/testuser/.vnc/vnc.log

Once you can get an exact error message you can often find the solution by copying and pasting it into Google...
 
Old 12-01-2004, 06:38 AM   #9
Vyrolan
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Registered: Dec 2004
Location: Kirksville, MO
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Did you ever find the solution to this? I have this exact same problem. I set it up from Gentoo-wiki and it worked beautifully... I hadn't used it in a while, but needed to yesterday and it does not work at all now. The KDM screen appears...and it accepts my username/password, but it never shows me KDE. The KDE processes are being executed...I can see them running using "ps", but nothng ever appears in the VNC window. Then after all of the processes for starting up VNC finish, the VNC viewer just closes saying that the connection was closed.

Any help on this issue would be appreciated...sometimes it is nice to have X...and I think akidd is right...it seems to be related to something recently updated by an emerge -u world for me.
 
Old 12-01-2004, 07:35 AM   #10
Vyrolan
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Registered: Dec 2004
Location: Kirksville, MO
Distribution: Gentoo
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Solution Found

The problem here is because of an update to PAM. A recent emerge broke the VNC terminal server, causing the "nothing appears after login" problem.

You can fix it by commenting out the following lines in /etc/security/pam_env.conf:

Code:
REMOTEHOST     DEFAULT= OVERRIDE=@{PAM_RHOST}
DISPLAY        DEFAULT=${REMOTEHOST}:0.0 OVERRIDE=${DISPLAY}
XAUTHORITY     DEFAULT= OVERRIDE=@{XAUTHORITY}
 
Old 12-25-2004, 07:01 PM   #11
fgeter
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Thanks, the PAM config file correction fixed my problem with KDE not starting.

Thanks again
 
  


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