How to get server session to lock when connected via xrdp

[BusterRaid]

Hi.
I cant seem to get the session to “lock” when connected via xrdp, either on-demand or via “Power management/Blank after X mintues”.
The device running xrdp server is a VM running Debian 12.5 Bookworm with xfce4 desktop and the client is Windows 10 Pro, connecting via "built it" Remote Desktop Client.

Connected “directly”, via VMWare Player:

When connected “directly”, via VMWare Player, I can lock the screen with:

light-locker-command -l

Or:

dm-tool lock

Or:

… if the display is set to “Blank after X minutes” in “Power Management”, the screen will automagically lock, after the allotted time.

The screen briefly goes black and then the greeter is presented.

... and examiningthe log (journalctl), there are many entries regarding closing and stopping stuff.

Connected via xrdp:

When connected via xrdp, issuing the following command in a Terminal (as the logged in user):

light-locker-command -l

… returns:

** Message: 17:45:28.147: Received error message from the locker: GDBus.Error:org.freedesktop.DBus.Error.ServiceUnknown: The name org.freedesktop.ScreenSaver was not provided by any .service files

... and examining the log (journalctl), there are just two entries:

Feb 22 18:35:36 XRDEB12VM xrdp-chansrv[5020]: [ERROR] clipboard_event_selection_request: unknown target text/plain;charset=utf-8
Feb 22 18:35:36 XRDEB12VM xrdp-chansrv[5020]: [ERROR] clipboard_event_selection_request: unknown target text/plain;charset=utf-8

... and looking at xrdp.log ,xrdp-sesman.log and /var/log/lightdm/seat0-greeter.log, there are no entries created when the above command is issued.

When issuing the following command in a Terminal (as the logged in user):

dm-tool lock

… returns:

Not running inside a display manager, XDG_SEAT_PATH not defined

Looking at “light-locker” (https://github.com/the-cavalry/light-locker/issues?q=rdp), I couldnt see any items regarding rdp.

Any help or ideas would be appreciated.
Thank you.

Client:
Windows 10 Pro x64 2H22
Remote Desktop Connection client.
Remote Desktop Connection Shell\Control Version: 10.0.19041
Remote Desktop Protocol 10.8

Server:
VM running under VMWare Player.
OS: Debian 12.5 Bookworm x86-64
Kernel: Linux 6.1.0-18-amd64

Software:
xorgxrdp/stable,now 1:0.9.19-1 amd64
xrdp/stable,now 0.9.21.1-1 amd64
light-locker/stable,now 1.8.0-3 amd64
xfce4/stable,now 4.18 all

Run via xrdp - systemctl status display-manager:

● lightdm.service - Light Display Manager
Loaded: loaded (/lib/systemd/system/lightdm.service; enabled; preset: enabled)
Active: active (running) since Thu 2024-02-22 09:53:49 GMT; 7h ago
Docs: man:lightdm(1)
Main PID: 677 (lightdm)
Tasks: 6 (limit: 4575)
Memory: 98.6M
CPU: 3min 11.487s
CGroup: /system.slice/lightdm.service
├─ 677 /usr/sbin/lightdm
├─11363 /usr/lib/xorg/Xorg :0 -seat seat0 -auth /var/run/lightdm/root/:0 -nolisten tcp vt7 -novtswitch
└─11441 lightdm --session-child 14 22

Run via VMWare - systemctl status display-manager:

● lightdm.service - Light Display Manager
Loaded: loaded (/lib/systemd/system/lightdm.service; enabled; preset: enabled)
Active: active (running) since Thu 2024-02-22 17:50:11 GMT; 29min ago
Docs: man:lightdm(1)
Main PID: 682 (lightdm)
Tasks: 5 (limit: 4575)
Memory: 150.1M
CPU: 18.423s
CGroup: /system.slice/lightdm.service
├─ 682 /usr/sbin/lightdm
└─3541 /usr/lib/xorg/Xorg :0 -seat seat0 -auth /var/run/lightdm/root/:0 -nolisten tcp vt7 -novtswitch

Run via xrdp - ME@XRDEB12VM:~$ env:

SESSION_MANAGER=local/XRDEB12VM:@/tmp/.ICE-unix/5016,unix/XRDEB12VM:/tmp/.ICE-unix/5016
XDG_CONFIG_DIRS=/etc/xdg
XDG_MENU_PREFIX=xfce-
DESKTOP_SESSION=xfce
GTK_MODULES=gail:atk-bridge
XDG_SESSION_TYPE=x11
PANEL_GDK_CORE_DEVICE_EVENTS=0
PULSE_SCRIPT=/etc/xrdp/pulse/default.pa
XDG_CURRENT_DESKTOP=XFCE
VTE_VERSION=7006
XRDP_SOCKET_PATH=/run/xrdp/sockdir
XRDP_PULSE_SOURCE_SOCKET=xrdp_chansrv_audio_in_socket_10
XDG_SESSION_CLASS=user
TERM=xterm-256colo
XRDP_SESSION=1
DISPLAY=:10.0
XRDP_PULSE_SINK_SOCKET=xrdp_chansrv_audio_out_socket_10
SHLVL=1
XDG_SESSION_ID=c10
XDG_RUNTIME_DIR=/run/user/1000
XDG_DATA_DIRS=/usr/share/xfce4:/usr/local/share/:/usr/share/:/usr/share
PATH=/usr/local/bin:/usr/bin:/bin:/usr/local/games:/usr/games
DBUS_SESSION_BUS_ADDRESS=unix:path=/run/user/1000/bus
UID=1000
_=/usr/bin/env

Run via VMWare- ME@XRDEB12VM:~$ env:

SESSION_MANAGER=local/XRDEB12VM:@/tmp/.ICE-unix/4305,unix/XRDEB12VM:/tmp/.ICE-unix/4305
XDG_CONFIG_DIRS=/etc/xdg
XDG_SESSION_PATH=/org/freedesktop/DisplayManager/Session2
XDG_MENU_PREFIX=xfce-
DESKTOP_SESSION=xfce
GTK_MODULES=gail:atk-bridge
XDG_SEAT=seat0
XDG_SESSION_DESKTOP=xfce
XDG_SESSION_TYPE=x11
PANEL_GDK_CORE_DEVICE_EVENTS=0
XAUTHORITY=/home/me/.Xauthority
XDG_GREETER_DATA_DIR=/var/lib/lightdm/data/me
XDG_CURRENT_DESKTOP=XFCE
VTE_VERSION=7006
XDG_SEAT_PATH=/org/freedesktop/DisplayManager/Seat0
XDG_SESSION_CLASS=user
TERM=xterm-256color
DISPLAY=:0.0
SHLVL=1
XDG_VTNR=7
XDG_SESSION_ID=32
XDG_RUNTIME_DIR=/run/user/1000
XDG_DATA_DIRS=/usr/share/xfce4:/usr/local/share/:/usr/share/:/usr/share
PATH=/usr/local/bin:/usr/bin:/bin:/usr/local/games:/usr/games
GDMSESSION=xfce
DBUS_SESSION_BUS_ADDRESS=unix:path=/run/user/1000/bus
_=/usr/bin/env

[matt335672]

• Log in on the VMWare player console.

• Find out the PID of the executable that provides org.freedesktop.ScreenSaver with this command:-

  dbus-send --session --print-reply --dest=org.freedesktop.DBus / org.freedesktop.DBus.GetConnectionUnixProcessID string:org.freedesktop.ScreenSaver
  

Then you can use ps -fp on that PID to find out what the executable is.

Here's an example from my Linux Mint machine running XFCE:-

$ dbus-send --session --print-reply --dest=org.freedesktop.DBus / org.freedesktop.DBus.GetConnectionUnixProcessID string:org.freedesktop.ScreenSaver
method return time=1708703155.300133 sender=org.freedesktop.DBus -> destination=:1.5157 serial=3 reply_serial=2
   uint32 3049
$ ps -fp 3049
UID          PID    PPID  C STIME TTY          TIME CMD
...         3049    2951  0 10:17 ?        00:00:00 xscreensaver-systemd -verbos

We can then figure out if that executable should be running in your XRDP session, and if it should, why it isn't.

[BusterRaid]

Thank you for the reply.

Via VMWare Player console:

$ dbus-send --session --print-reply --dest=org.freedesktop.DBus / org.freedesktop.DBus.GetConnectionUnixProcessID string:org.freedesktop.ScreenSaver

... returns:

method return time=1708707794.676135 sender=org.freedesktop.DBus -> destination=:1.830 serial=3 reply_serial=2
uint32 8428

Looking up that PID returns:

UID PID PPID C STIME TTY TIME CMD
xxxxx+ 8428 8264 0 16:41 ? 00:00:00 light-locker

[matt335672]

Try running light-locker by hand in your session and see what happens.

[BusterRaid]

All via xrdp connection, "normal" user:

$ light-locker

... Returns:

** (light-locker:12656): ERROR **: 18:33:18.210: Environment variable XDG_SESSION_PATH not set. Is LightDM running?
Trace/breakpoint trap

The absence of "XDG_SESSION_PATH" is as in the OP.
For VMWare, XDG_SESSION_PATH is set.
Via xrdp, it is not present.

Running:

$ /usr/sbin/lightdm

... Returned:

Only root can run Light Display Manager. To run as a regular user for testing run with the --test-mode flag.

... Running:

$ /usr/sbin/lightdm --test-mode

Returned:

Running inside an X server requires Xephyr to be installed but it cannot be found. Please install it or update your PATH environment variable.

I then ran (still via xrdp, "normal" user):

$ ps -ef | grep lightdm

... And it rather surprisingly returned:

root 682 1 0 16:48 ? 00:00:00 /usr/sbin/lightdm
root 12022 682 0 18:32 tty7 00:00:00 /usr/lib/xorg/Xorg :0 -seat seat0 -auth /var/run/lightdm/root/:0 -nolisten tcp vt7 -novtswitch
root 12029 682 0 18:32 ? 00:00:00 lightdm --session-child 19 22
lightdm 12033 1 0 18:32 ? 00:00:00 /lib/systemd/systemd --user
lightdm 12034 12033 0 18:32 ? 00:00:00 (sd-pam)
lightdm 12049 12033 0 18:32 ? 00:00:00 /usr/bin/pulseaudio --daemonize=no --log-target=journal
lightdm 12050 12029 0 18:32 ? 00:00:01 /usr/sbin/lightdm-gtk-greeter
lightdm 12055 12033 0 18:32 ? 00:00:00 /usr/bin/dbus-daemon --session --address=systemd: --nofork --nopidfile --systemd-activation --syslog-only
lightdm 12059 12033 0 18:32 ? 00:00:00 /usr/libexec/at-spi-bus-launcher
lightdm 12066 12059 0 18:32 ? 00:00:00 /usr/bin/dbus-daemon --config-file=/usr/share/defaults/at-spi2/accessibility.conf --nofork --print-address 11 --address=unix:path=/run/user/107/at-spi/bus
lightdm 12068 12033 0 18:32 ? 00:00:00 /usr/libexec/gvfsd
lightdm 12073 12033 0 18:32 ? 00:00:00 /usr/libexec/gvfsd-fuse /run/user/107/gvfs -f
root 12099 682 0 18:32 ? 00:00:00 lightdm --session-child 14 22
lightdm 12101 12033 0 18:32 ? 00:00:00 /usr/libexec/at-spi2-registryd --use-gnome-session
chrisbe+ 12695 12650 0 18:37 pts/0 00:00:00 grep lightdm

... Suggestive to my not so clear eye, that lightdm is running.
Checking the lightdm.service, the following is seen:

lightdm.service - Light Display Manager
Loaded: loaded (/lib/systemd/system/lightdm.service; enabled; preset: enabled)
Active: active (running) since Thu 2024-02-22 17:50:11 GMT; 1 day 1h ago
Docs: man:lightdm(1)
Main PID: 682 (lightdm)
Tasks: 6 (limit: 4575)
Memory: 95.5M
CPU: 54.737s
CGroup: /system.slice/lightdm.service
├─ 682 /usr/sbin/lightdm
├─13999 /usr/lib/xorg/Xorg :0 -seat seat0 -auth /var/run/lightdm/root/:0 -nolisten tcp vt7 -novtswitch
└─14081 lightdm --session-child 15 22

Feb 23 18:32:45 XRDEB12VM lightdm[12029]: Error getting user list from org.freedesktop.Accounts: GDBus.Error:org.freedesktop.>
Feb 23 18:32:45 XRDEB12VM lightdm[12029]: pam_unix(lightdm-greeter:session): session opened for user lightdm(uid=107) by (uid>
Feb 23 18:39:03 XRDEB12VM lightdm[13395]: gkr-pam: unable to locate daemon control file
Feb 23 18:39:03 XRDEB12VM lightdm[13395]: gkr-pam: stashed password to try later in open session
Feb 23 18:39:03 XRDEB12VM lightdm[13395]: Error getting user list from org.freedesktop.Accounts: GDBus.Error:org.freedesktop.>
Feb 23 18:39:03 XRDEB12VM lightdm[682]: g_dbus_connection_call_sync_internal: assertion 'G_IS_DBUS_CONNECTION (connection)' f>
Feb 23 18:39:03 XRDEB12VM lightdm[13395]: pam_unix(lightdm:session): session opened for user chrisbennett(uid=1000) by (uid=0)
Feb 23 18:39:03 XRDEB12VM lightdm[13395]: gkr-pam: unlocked login keyring
Feb 23 18:49:19 XRDEB12VM lightdm[14007]: Error getting user list from org.freedesktop.Accounts: GDBus.Error:org.freedesktop.>
Feb 23 18:49:19 XRDEB12VM lightdm[14007]: pam_unix(lightdm-greeter:session): session opened for user lightdm(uid=107) by (uid>
~

[matt335672]

@BusterRaid - thanks for that investigative work. There's some useful information there.

My guess is that you've got lightdm running to permit logins to the console (or 'via VMWare player' as you describe it above). When the user logs in at the console, lightdm makes a note of the user session so that it can control not only the screen locking but user switching.

My guess is that it sets XDG_SESSION_PATH appropriately so that light-locker can communicate with it over D-Bus.

Because lightdm doesn't know anything about xrdp sessions, I don't think there will be a simple way to make the lightdm lock screen work with xrdp.

From the little research I've done, it looks like xscreensaver might be able to replace this though. Can you try installing and running xscreensave in an xrdp session and see if it works for you? If so, we'll figure out a way to starting when you log in over xrdp.

[BusterRaid]

Hi.
As per suggestion, I uninstalled light-locker:

apt remove light-locker

... Installed xscreensaver:

apt update
apt install xscreensaver

Rebooted.

Screen lock (and screen saver) works on VMWare Play console and via xrdp.

Happy for this to be closed or I can help out with more testing regarding "light-locker".

Thank you.

[matt335672]

Thanks @BusterRaid - that's really useful information.

I'll close this then, as I'm pretty sure we can't get lightdm to recognise an xrdp session.