HOWTO XDMCP for 18.04
HOWTO and FAQ: XDMCP for 18.04 ESR
Since I seem to be one of the few people who use it, even with all the "thin computing" this and should be taking place... Certain factions in the Linux arena seem to do their best to break, damage, and remove this as much as possible.
So...
First... the background.
SDDM which is the new hotness window manager, is not so hot. It has no support for XDMCP... The KDE manager, KDM was assassinated recently for some reason!! (
??)
So that leaves LightDM as the last manager standing...
The gotcha in 18.04 is there is NO KDE GREETER TO USE WITH LightDM! ! ! (Again removed why??)
You will get half baked answers on how to do this which might work for the standard Debian and other related distros which are NOT USING KDE! When KDE comes into play, these solutions will leave you with NO X WINDOW DESKTOP!
The usual result is a purple screen with "Failed to init session..." errors and there it dies...
So the fix?
You REQUIRE LightDM AND a GREETER! So how to ensure this happens?
You may or may not need the "settings" packages.. I chose to add them just for completeness.
Do this, and it will run dpkg-reconfigure as part of the setup, SELECT LightDM for your manager... and on you go...
NEXT
You have to create a file to enable XDMCP!
Just like in 16.04, and 14.04...and the WRONG AND MISSING info on every search result is this:
THIS FILE DOES NOT EXIST BY DEFAULT AND NEVER HAS EXISTED BY DEFAULT!
Just do this:
Save the file and then you either need to
1)
OR
2) Reboot
Either will enable the XDMCP option...
Then you can use your favorite X program to access... via LAN or SSH...
You can explore the exact options needed... retro is optional... I like it as it functions the way remote X should...
And with that..
BAM!
you have remote access to your system!
WARNING! DO NOT I REPEAT DO NOT INSTALL LightDM via SYNAPTIC! ! ! ! ! ! ! It will attempt to bring in over 300MB worth of stuff that is NOT NEEDED! !!
! ! What ever the settings are in synaptic something is seriously wrong! It likely will also BREAK YOUR SYSTEM if you do it...DON'T DO IT! USE CLI apt-get!!!!
The above works, and it brings in the above, and only the above...This was done one a FRESH INSTALL from USB stick, then updated to full latest releases including 4.15-049 kernel... Then the above was done... Works great...
There is ONE BUG.. which is not releated LightDM, from what I am finding... When you login remotely you will get an error "Can not manage network connections..." This seems to be some issue with polkit Which I've not used in the past... The workaround right now is enter your sudo password for the box...
BUT
XDMCP works...
Since I seem to be one of the few people who use it, even with all the "thin computing" this and should be taking place... Certain factions in the Linux arena seem to do their best to break, damage, and remove this as much as possible.
So...
First... the background.
SDDM which is the new hotness window manager, is not so hot. It has no support for XDMCP... The KDE manager, KDM was assassinated recently for some reason!! (
??) So that leaves LightDM as the last manager standing...
The gotcha in 18.04 is there is NO KDE GREETER TO USE WITH LightDM! ! ! (Again removed why
??)You will get half baked answers on how to do this which might work for the standard Debian and other related distros which are NOT USING KDE! When KDE comes into play, these solutions will leave you with NO X WINDOW DESKTOP!
The usual result is a purple screen with "Failed to init session..." errors and there it dies...
So the fix
?You REQUIRE LightDM AND a GREETER! So how to ensure this happens?
Code:
sudo apt-get install lightdm lightdm-gtk-greeter lightdm-settings lightdm-gtk-greeter-settings
Do this, and it will run dpkg-reconfigure as part of the setup, SELECT LightDM for your manager... and on you go...
NEXT
You have to create a file to enable XDMCP!
Just like in 16.04, and 14.04...and the WRONG AND MISSING info on every search result is this:
THIS FILE DOES NOT EXIST BY DEFAULT AND NEVER HAS EXISTED BY DEFAULT!
Just do this:
Code:
cd /etc/lightdm/ sudo nano lightdm.conf in the file paste: [XDMCPServer] enabled=true port=177
1)
Code:
sudo systemctl restart lightdm
2) Reboot
Either will enable the XDMCP option...
Then you can use your favorite X program to access... via LAN or SSH...
Code:
$ Xephyr -retro -screen 1368x768 :2 -query IP/host
And with that..
BAM!
you have remote access to your system!
WARNING! DO NOT I REPEAT DO NOT INSTALL LightDM via SYNAPTIC! ! ! ! ! ! ! It will attempt to bring in over 300MB worth of stuff that is NOT NEEDED! !!
! ! What ever the settings are in synaptic something is seriously wrong! It likely will also BREAK YOUR SYSTEM if you do it...DON'T DO IT! USE CLI apt-get!!!!
The above works, and it brings in the above, and only the above...This was done one a FRESH INSTALL from USB stick, then updated to full latest releases including 4.15-049 kernel... Then the above was done... Works great...
There is ONE BUG.. which is not releated LightDM, from what I am finding... When you login remotely you will get an error "Can not manage network connections..." This seems to be some issue with polkit
Which I've not used in the past... The workaround right now is enter your sudo password for the box... BUT
XDMCP works...
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