Xdmcp

[boondocks]

A few minutes ago, I finished installing Ubuntu on a remote desktop.
Just walked back to my desk.

On that remote Ubuntu desktop, I would like to turn on the XDMCP feature.

If I was sitting at that remote Ubuntu desktop, I would make the following change:
System-->Administration-->Login Window-->Remote-->Style:Same as Local

But I am not sitting at the remote Ubuntu desktop.
I only have SSH access to the remote Ubuntu desktop.
So how do I make the same change from the command line?

[asmoore82]

SSH can provide X tunneling for individual Apps with the ``-X'' switch


me@local ~$ ssh -X <remote_admin_user>@<remote_machine>
me@remote ~$ sudo echo
me@remote ~$ gksudo gdmsetup
^^the `sudo echo` is just to temporarily store sudo authentication -
gksudo can be dog slow over X tunneling :biggrin:

[boondocks]

asmoore82, Thanks for the response.

That helped. I am able to run gdmsetup on the remote system now.

[boondocks]

Yes, it is dog slow.
So instead of running the full gdm, I was trying to run specific admin apps like "users-admin".

But regardless of
"gksudo users-admin"
or
"sudo users-admin"


I can get the Users Settings window but the Unlock button is gray.
So I cannot edit any user settings.
I have root access on this remote system.

So how do I get the Unlock button to not be gray.

(I walked back to the remote system and login via gdm.
Then I typed "users-admin" and it works.)

[asmoore82]

for Apps that have Policy Kit integrated(the "Unlock" button),
you'll actually want to run them as your plain user account without gksudo

and yet for other Apps such as `gdmsetup` you need the gksudo ...
It's a bit of a strange Duopoly at this point in its evolution.

[boondocks]

I tried that...


users-admin

(users-admin:17942): Gtk-WARNING **: GtkSpinButton: setting an adjustment with non-zero page size is deprecated

(users-admin:17942): Gtk-WARNING **: GtkSpinButton: setting an adjustment with non-zero page size is deprecated

(users-admin:17942): Gtk-WARNING **: GtkSpinButton: setting an adjustment with non-zero page size is deprecated

(users-admin:17942): Gtk-WARNING **: GtkSpinButton: setting an adjustment with non-zero page size is deprecated

(users-admin:17942): Gtk-WARNING **: GtkSpinButton: setting an adjustment with non-zero page size is deprecated

(users-admin:17942): Gtk-WARNING **: GtkSpinButton: setting an adjustment with non-zero page size is deprecated

(users-admin:17942): Gtk-WARNING **: GtkSpinButton: setting an adjustment with non-zero page size is deprecated
I get the Users Settings window.
It does not ask for the admin password and the Unlock button is still gray.
And when I hover the mouse over the "unlock" button, it says:
"This action is not allowed"

[asmoore82]

D'oh!! I forgot that Policy Kit also assumes by default that certain Admin actions
should only be grant-able on local login.

You could tweak these settings at "System -> Administration -> Authorizations"

[boondocks]

You could tweak these settings at "System -> Administration -> Authorizations"

I am looking at the Authorizations screen.

policykit

Revoke authorizations from other users
Read authorizations of other users
Modify defaults for implicit authorizations
Grant authorizations to other users

It is not clear to me which/how these option(s) would allow me (the Admin) to access XDmcp from a remote system.
Could you please give me some direction here?