Re: [gdm-list] gdm-list Digest, Vol 120, Issue 1

[anonymous <johnandsara2 cox net>]

I’m sorry I did forget a couple of simple strategies gdm might agree with.

First, of course, look through all files in /etc/gdm and be sure to read the (manpages) for configuration 
files of gdm.  (note a problem: you might easily think you’ve solved your problem an left a hole elsewhere.  
though that may be the case with whatever ‘solution’ you find.  test well if you care.)

A next most simple is to ask the persons who are editing gdm (see changelogs, see GIT source code side gdm is 
being released *from*) to make that an option in gdm config.  It’s a reasonable request.

Infact it isn’t only reasonable: people have been making the request of “point of sale style login” (no 
login, and only designated user can use desktop) practically since gdm was released!

the following will tell X Windows (not wayland or what else) that  X display n from host HOSTNAME can only be 
the listed users.  However one of the users may need to be root, which would still allow “log in as different 
user as root” (with password of course)

-------------------
FILE: /etc/Xn.HOSTNAME
root
user1
—————————

this is only for using startx and that depends on your (linux) distro

-------------------
FILE: /etc/X11/Xserver
root
user1
—————————

the following can be more specific, what user can have what kind of terminal.  a text terminal is a tty, but 
X Windows is called an X Terminal.  i can’t say how to modify this file - but usertty(1) may enable some 
‘pros’ to know what to do when the manpage is read.

FILE: /etc/usertty OR FILE:/etc/securetty

lastly pam(1) (see man pam).

this is for ‘pam controlled’ tty (see above)

FILE: /etc/securetty

these files effect pam login

FILE: /etc/pam.d/gdm

and these pam(1) config files effect who can use video, sound, and more.  the jist here is if you allow only 
one user (say, user1) to use video?  then only user1 is gong to be able to use X Windows (problem?  if root 
needs access to show login screen, and if your trying to prevent a root login via xdm.  if you are?  then you 
really need to talk to someone who knows allot about it - it would not be a 1-2-3 answer given by email)

FILE: /etc/security/*


> On Oct 4, 2016, at 8:00 AM, gdm-list-request gnome org wrote:
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> Today's Topics:
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>   1.  Disable User Switching on lockscreen (Laverne Schrock)
>
>
> ----------------------------------------------------------------------
>
> Message: 1
> Date: Mon, 3 Oct 2016 18:26:40 -0500
> From: Laverne Schrock <schr1230 morris umn edu>
> To: gdm-list gnome org
> Subject: [gdm-list] Disable User Switching on lockscreen
> Message-ID:
>       <CABMX+7RzgGQZcJN47XeFmCAuAQ1i4MqAajQtFMtq7ay1ET6qRQ mail gmail com>
> Content-Type: text/plain; charset=UTF-8
>
> Hi,
>
> I have a Fedora 24 system on which I would like to disable user switching.
> By following the steps listed here:
> https://access.redhat.com/documentation/en-US/Red_Hat_Enterprise_Linux/7/html/Desktop_Migration_and_Administration_Guide/lockdown-logout.html
> I can remove the "Switch User" button from the system menu. However,
> the user can still lock the screen and then click "Log in as another user"
> right in GDM which defeats the purpose.
>
> So here is the question. Is there a way to enable screen locking and disable
> user switching on modern GDM?
>
> Thanks,
> Laverne Schrock
>
>
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