LinuxQuestions.org - LightDM with XDMCP on a VM

Hi!

I have a Virtual Machine which runs Ubuntu 11.10 and want to use it as a headless XDMCP server using LightDM.

I've installed all required software (installing lubuntu-desktop was the easiest way) and made some changes to the lightdm config to enable the XDMCP server.

However, on connecting to the server via my Mac using Xephyr I just get a black screen.

During some investigation I stumbled upon the lightdm logd:

lightdm.log:

Code:

[+0.00s] DEBUG: Logging to /var/log/lightdm/lightdm.log

[+0.00s] DEBUG: Starting Light Display Manager 1.0.6, UID=0 PID=6457

[+0.00s] DEBUG: Loaded configuration from /etc/lightdm/lightdm.conf

[+0.00s] DEBUG: Using D-Bus name org.freedesktop.DisplayManager

[+0.00s] DEBUG: Registered seat module xlocal

[+0.00s] DEBUG: Registered seat module xremote

[+0.00s] DEBUG: Starting XDMCP server on UDP/IP port 177

[+0.01s] DEBUG: Acquired bus name org.freedesktop.DisplayManager

[+22.74s] DEBUG: Got Query(authentication_names=[])

[+22.74s] DEBUG: Send Willing(authentication_name='' hostname='' status='')

[+22.85s] DEBUG: Got Request(display_number=1 connections=[(0, 0A5A5AB1) (0, 0A5A5ABE) (6, FE8000000000000002254BFFFEFCD268) (6, FE8000000000000062C547FFFE09DB12)] authentication_name='' authentication_data= authorization_names=['MIT-MAGIC-COOKIE-1' 'XDM-AUTHORIZATION-1'] manufacturer_display_id='')

[+22.85s] DEBUG: Send Accept(session_id=59614 authentication_name='' authentication_data= authorization_name='MIT-MAGIC-COOKIE-1' authorization_data=AF973ADA5C0D8FBC1499C00CDABB1FF9)

[+22.86s] DEBUG: Timing out unmanaged session 59614

[+22.87s] DEBUG: Got Manage(session_id=59614 display_number=1 display_class='MIT-unspecified')

[+22.87s] DEBUG: Send Refuse(session_id=59614)

[+22.89s] DEBUG: Got Request(display_number=1 connections=[(0, 0A5A5AB1) (0, 0A5A5ABE) (6, FE8000000000000002254BFFFEFCD268) (6, FE8000000000000062C547FFFE09DB12)] authentication_name='' authentication_data= authorization_names=['MIT-MAGIC-COOKIE-1' 'XDM-AUTHORIZATION-1'] manufacturer_display_id='')

[+22.89s] DEBUG: Send Accept(session_id=19724 authentication_name='' authentication_data= authorization_name='MIT-MAGIC-COOKIE-1' authorization_data=16559F94E4E33E1B0C9D1493A06AA13E)

[+22.90s] DEBUG: Timing out unmanaged session 19724

[+22.91s] DEBUG: Got Manage(session_id=19724 display_number=1 display_class='MIT-unspecified')

[+22.91s] DEBUG: Send Refuse(session_id=19724)

[+22.93s] DEBUG: Got Request(display_number=1 connections=[(0, 0A5A5AB1) (0, 0A5A5ABE) (6, FE8000000000000002254BFFFEFCD268) (6, FE8000000000000062C547FFFE09DB12)] authentication_name='' authentication_data= authorization_names=['MIT-MAGIC-COOKIE-1' 'XDM-AUTHORIZATION-1'] manufacturer_display_id='')

[+22.93s] DEBUG: Send Accept(session_id=49293 authentication_name='' authentication_data= authorization_name='MIT-MAGIC-COOKIE-1' authorization_data=BDF9C2F84928A783DA94A401233657D9)

[+22.94s] DEBUG: Timing out unmanaged session 49293

[+22.95s] DEBUG: Got Manage(session_id=49293 display_number=1 display_class='MIT-unspecified')

[+22.95s] DEBUG: Send Refuse(session_id=49293)

And x-0.log:

Code:

X.Org X Server 1.10.4

Release Date: 2011-08-19

X Protocol Version 11, Revision 0

Build Operating System: Linux 2.6.24-29-server x86_64 Ubuntu

Current Operating System: Linux vps3005.xlshosting.net 3.0.0-15-virtual #26-Ubuntu SMP Fri Jan 20 20:57:08 UTC 2012 x86_64

Kernel command line: root=/dev/xvda1 ro root=/dev/xvda1 ro

Build Date: 19 October 2011  05:21:26AM

xorg-server 2:1.10.4-1ubuntu4.2 (For technical support please see http://www.ubuntu.com/support) 

Current version of pixman: 0.22.2

        Before reporting problems, check http://wiki.x.org

        to make sure that you have the latest version.

Markers: (--) probed, (**) from config file, (==) default setting,

        (++) from command line, (!!) notice, (II) informational,

        (WW) warning, (EE) error, (NI) not implemented, (??) unknown.

(==) Log file: "/var/log/Xorg.0.log", Time: Wed Jan 25 12:07:05 2012

(==) Using system config directory "/usr/share/X11/xorg.conf.d"

(EE) open /dev/fb0: No such file or directory

(EE) No devices detected.



Fatal server error:

no screens found



Please consult the The X.Org Foundation support 

        at http://wiki.x.org

 for help. 

Please also check the log file at "/var/log/Xorg.0.log" for additional information.



 ddxSigGiveUp: Closing log

I see some "Send Refuse" notices, maybe these have something to do with it? Also, I see in the x log that the display /dev/fb0 cannot be openend, which is obvious as it is a virtual machine.

My lightdm.conf is as follows (might miss or have unneeded options):

Code:

[LightDM]

start-default-seat=false

greeter-user=lightdm

#minimum-display-number=0

minimum-vt=0

[SeatDefaults]

greeter-session=unity-greeter

user-session=ubuntu

minimum-vt=vt0

[XDMCPServer]

enabled=true

Does anyone know how to use LightDM using no physical graphics card and only using it for it's XDMCP functionality? I think I'm missing some critical options, but do not know how to solve this...

Any help is appreciated!