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Description: Candidates should be able to describe the basic features and configuration of the LightDM display manager. This objective covers awareness of the display managers XDM (X Display Manger), GDM (Gnome Display Manager) and KDM (KDE Display Manager).
Key Knowledge Areas:
- Basic configuration of LightDM
- Turn the display manager on or off
- Change the display manager greeting
- Awareness of XDM, KDM and GDM
Terms and Utilities:
lightdm /etc/lightdm/
start X
telinit 5 # switch to X GUI
or permanently change in /etc/inittab
id:5:initdefault:
XDM
/etc/X11/xdm/xdm-config DisplayManager.requestPort: 0 # 177 to enable /etc/X11/xdm/Xaccess, to permit remote access
KDM
/etc/X11/kdm or /etc/kde/kdm
GDM
/etc/X11/gdm or /etc/gdm
lightdm
# systemctl stop lightdm.service # systemctl start lightdm.service /usr/share/lightdm/lightdm.conf.d/*.conf /etc/lightdm/lightdm.conf.d/*.conf /etc/lightdm/lightdm.conf oldhorse@dclab:/etc/lightdm$ cat users.conf # User accounts configuration [UserList] minimum-uid=500 hidden-users=nobody nobody4 noaccess hidden-shells=/bin/false /usr/sbin/nologin System provided configuration is stored in /usr/share/lightdm/lightdm.conf.d/*.conf and is not user editable. System administrators can override this configuration in /etc/lightdm/lightdm.conf.d/*.conf and /etc/lightdm/lightdm.conf. Files are read in the above order and combined together to make the LightDM configuration.
X remote access
X for remote access, you must remember that the X server runs on the user’s computer, while the X clients run on the remote system.
1) xhost +zeus env|grep DISP # get local X server IP and display number ssh zeus # remote client setenv DISPLAY: Xclient back to X server xhost -zeus 2) ssh -X root@zeus Xclient
enable X access
GDM /etc/X11/gdm/gdm.conf # old DisallowTCP=false /etc/gdm/custom.conf # new DisallowTCP=false KDM/XDM /etc/X11/xdm line contains the string -nolisten tcp # remove
VNC
Virtual Network Computing (VNC)
VNC runs a special X server on the computer that is designed to be used from a distance, and a special VNC client runs on the computer at which you sit. You use the client to contact the server directly.