x11vnc shutting down on Intrepid login

[krunge]

* I run (/usr/bin/x11vnc -localhost -o /var/log/x11vnc.log -forever -bg)

And I cannot connect to GDM. I logon to the vmware machine via GDM and then rerun the command. I can connect, but when I 'logoff' x11vnc dies.

You will need to run x11vnc as root and also supply the mit-magic-cookie file via -auth option.

I.e. maybe '-auth /var/lib/gdm/:0.Xauth', but I am not sure of the exact location on your distro, use 'ps wwwwwaux | grep auth' to find it.

Also add '-display :0'

So try something like that and see what gdm (or X server) does.

I don't see "x11vnc" anywhere in the syslog, xorg log, or gdm log.

There won't be any. We're looking for messages from gdm why it is exiting/crashing.

[MisterB]

I tried adding the auth and display options without success. However, I did find this error in the syslog:

gdm[8748]: WARNING: gdm_slave_xioerror_handler: Fatal X error - Restarting :0

Not sure where else I can look to get more information about this error.

[krunge]

I did find this error in the syslog:

gdm[8748]: WARNING: gdm_slave_xioerror_handler: Fatal X error - Restarting :0

Not sure where else I can look to get more information about this error.

I have a test machine in my basement with ubuntu on it and I upgraded it to 8.10. I was able to reproduce this problem.

It is the X server itself that is crashing. From /var/log/Xorg.0 (actually Xorg.0.old):

Backtrace:
0: /usr/X11R6/bin/X(xf86SigHandler+0x79) [0x80c3009]
1: [0xb7f89400]
2: /usr/X11R6/bin/X [0x8158279]
3: /usr/X11R6/bin/X(CallCallbacks+0x4e) [0x80909ae]
4: /usr/X11R6/bin/X(XaceHook+0x7e) [0x815702e]
5: /usr/X11R6/bin/X(ProcXFixesGetCursorImageAndName+0x8b) [0x8147e9b]
6: /usr/X11R6/bin/X [0x814639c]
7: /usr/X11R6/bin/X(Dispatch+0x34f) [0x808c89f]
8: /usr/X11R6/bin/X(main+0x47d) [0x8071d1d]
9: /lib/tls/i686/cmov/libc.so.6(__libc_start_main+0xe5) [0xb7b93685]
10: /usr/X11R6/bin/X [0x8071101]
Saw signal 11.  Server aborting.

Please verify that all of you get the same X server crash.

It is pretty serious that a simple X application like x11vnc can make the X server (running as root) have a segmentation violation and crash. Potentially a security issue as well.

Note by the 'ProcXFixesGetCursorImageAndName' above, x11vnc was trying to retrieve the mouse cursor shape and image at the time.

So a workaround is to apply the '-noxfixes' option to the x11vnc command line.

Please verify that -noxfixes avoids the crash for all of you.

If you don't like the few fixed mouse cursors under -noxfixes, you will have to log in twice via the VNC viewer, e.g.:

1) Put KillInitClients=true (not false) in gdm.conf-custom
2) Put the x11vnc start line in BOTH /etc/gdm/Init/Default and /etc/gdm/PreSession/Default
3) Restart everything

This way when you connect via VNC and login at the GDM greeter x11vnc will be disconnected after you log in. Then the x11vnc in PreSession/Default will be running and you connect to it with your VNC viewer a 2nd time. Then you will have all the xfixes mouse cursors.

[bearda]

I experienced the same problem trying to set up a headless Via Artigo system. I've even got the exact same backtrack in my X server logs. On the plus side, the -noxfixes switch seems bypass the problem completely with x11vnc executing out of xinetd (no changing the gdm startup script).

Thanks!

[krunge]

I experienced the same problem trying to set up a headless Via Artigo system. I've even got the exact same backtrack in my X server logs. On the plus side, the -noxfixes switch seems bypass the problem completely with x11vnc executing out of xinetd (no changing the gdm startup script).

I reported the problem to Xorg: http://bugs.freedesktop.org/show_bug.cgi?id=18451


BTW, if a person is willing to build x11vnc version 0.9.6 from the upstream source tarball, it has an option "-reopen" that works around this problem fairly well.

When using x11vnc's "-reopen" one does not specify KillInitClients=false to GDM, you either leave GDM in its default configuration or set to "true".

Then, when you login with GDM through x11vnc, GDM tries to kill x11vnc, but instead x11vnc just waits a few seconds and then tries to reopen the X display. It seems to work around this problem pretty well, and gives the full cursor shape (no need for -noxfixes).

Going forward, "-reopen" will probably become the preferred way to work around GDM's KillInitClients behavior.

http://www.karlrunge.com/x11vnc/x11v...tml#opt-reopen

[MisterB]

I can confirm that the -noxfixes option is working as described. I have to connect twice, but the login persists.

I haven't tried the -reopen option yet, but may try later this week.

Thanks!

[krunge]

I can confirm that the -noxfixes option is working as described. I have to connect twice, but the login persists.

Thanks.

BTW for x11vnc -noxfixes when using GDM with KillInitClients=false properly configured (gdm.conf-custom, or where ever) you should only need to connect once. Check if that works.

[GenPFault]

I can confirm that the -noxfixes option is working as described. I have to connect twice, but the login persists.

I haven't tried the -reopen option yet, but may try later this week.

Thanks!

-reopen seems to work (stock gdm.conf) with a self-compiled 0.9.6. checkinstall is your friend!

[hatmancan]

i am asking the following question?i tried to install kubuntu 8.10 to my hard drive..i waited for almost 5 hrs to download and when it did i now cannot log into my system..
i was reading this thread and thought maybe i have the same problem.
to give you some idea of my problems here they are.
dave@dave-desktop;~fglrxinfo
display: :0.0 screen:0
Opengl vendor string:S3 Graphic Inc
Opengl renderer string:Mesa dri pro savageDDR 20061110 AGP1x x86/MMX/SSE2
Opengl version string:1.2 Mesa 7.0.3-RC2
Segmentation Fault
dave@dave-desktop~$

i then ran sudo dpkg-reconfigure -phigh xserver-xorg
error message
xserver-xorg postinst warningverwriting possibly-customised configuration file;backup in /etc/x11/xorg.conf.20081108214244

so i ran sudo dpkg --configure-a
after that i have a list of errors as well if you need.

i have to switch from windows and this drive to get some answers..
i do have a ubuntu cd as well
2 hard drives one with ubuntu and one with windows
ps..i have also tried many other things to no avail
one being where i get to a screen with options to repair 4 different items,but neither will work

could someone please help me with this post

[krunge]

i am asking the following question?i tried to install kubuntu 8.10 to my hard drive... i now cannot log into my system..
i was reading this thread and thought maybe i have the same problem.

From what you have said, I don't think it is the same problem. You might want to start a separate thread.