Linux: XDMCP summary

XDMCP

locally – and locally only

Installer XDM

Archlinux

# pacman -S xorg-xdm

Ubuntu

# apt-get install xdm

When installing select xdm as default login manager

Edit as root

# nano /etc/X11/xdm/Xaccess
## remove remark (#) from the line reading
#*        #any host can get a login window

# nano /etc/X11/xdm/Xservers
##add remark (#) for the line - probably last - reading
:0 local ..(rest omitted)

# nano /etc/X11/xdm/xdm-config
## add remark (!) for the line - probably last - reading
DisplayManager.requestPort:    0

Arch: XDMCP

XDMCP desktop over LAN

Install XDM, LightDM and a greeter

$ sudo pacman -S xorg-xdm lightdm lightdm-gtk-greeter

/etc/X11/xdm/Xaccess => remove # at beginning of line

#*                  #any host can get a login window    

/etc/X11/xdm/Xservers => insert # at beginning of line

:0 local /usr/bin/X :0

/etc/X11/xdm/xdm-config => insert ! at beginning of line

DisplayManager.requestPort: 0

/etc/lightdm/lightdm.conf => edit section [XDMCPServer]

[XDMCPServer]
enabled=true
port=177
#key=

su

$ su -l root
# xdm -config /etc/X11/xdm/xdm-config
# exit

Activate and start LightDM

$ sudo systemctl enable lightdm
$ sudo systemctl start lightdm

Install Xming on Windows.

I recommend the donation approach. These versions are much-much than community version.