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  1. #1
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    F18 lightdm login banner user list suppress

    To help improve security, many orgs require a console gui login to suppress a list of valid usernames, require a user to type both a valid username plus its associated password, and also to display a login security text banner consisting of a few hundred characters typically on several lines of text.

    Setting this up under the past few Fedora releases has become increasingly mysterious and difficult.

    My latest F18 install is using alternatives of xfce and mate desktop environments, and I see that the display manager is now lightdm. I've located the lightdm configuration area under /etc/lightdm/, but it is not clear (to me) how to make changes under this directory to tell lightdm to suppress the user list, require both username and password login authentication, and provide a warning text banner on the console login screen. The system is using the standard graphical.target (old runlevel 5) type of console environment.

    E.g. I tried setting greeter-hide-users=true in one of the lightdm config files, but this appeared to have no effect (after a reboot). And I could not find any configuration file option related to a login banner text message.

    How does one configure lightdm under F18 to suppress the user list, require both username and password, and display a text banner on the console login screen?

    This capability is a fundamental security policy requirement within many organizations, and systems cannot be put into production without it.

    Thanks.

  2. #2
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    Re: F18 lightdm login banner user list suppress

    /etc/lightdm/users.conf says:
    # NOTE: If you have AccountsService installed on your system, then LightDM will
    # use this instead and these settings will be ignored
    The accountsservice package appears to be required by lightdm and lightdm-gtk, so configuring
    users must be done in /etc/dbus-1/system.d/org.freedesktop.Accounts.conf, or one of the other
    xml files in there. Good luck with that.

  3. #3
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    Re: F18 lightdm login banner user list suppress

    I do not understand why it is not working in your case. Few lines from my /etc/lightdm/lightdm.conf file

    Code:
    [...]
    
    greeter-session=lightdm-greeter
    greeter-hide-users=true
    greeter-allow-guest=false
    allow-guest=false
    
    [ ... ]
    This is working for me in my VM, two bare metal installs of F18 and in Xubuntu!

  4. #4
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    Re: F18 lightdm login banner user list suppress

    Sonoran and nonamedotc, many thanks for your replies.

    My F18 has accountsservice installed, and systemctl shows that it is running. But nothing under /etc/dbus-1/system.d/ looks obviously related to the originally stated problem.

    A second reboot after setting greeter-hide-users=true in /etc/lightdm/lightdm.conf made the greeter's list of users go away, and I'm now seeing the desired username and password dialogue on the console login screen. This is now consistent with nonamedotc's experiences, and solves half of the originally stated problem.

    The problem of displaying security login banner text on the console login screen remains.

    I'm guessing that the greeter being used by lightdm is /usr/sbin/lightdm-gtk-greeter. (Hints for this are in /etc/lightdm/lightdm.conf, /etc/alternatives/lightdm-greeter, etc.)

    There is a (not very human readable) xml configuration file in /usr/share/lightdm-gtk-greeter/greeter.ui. I wonder if something could be done with this file to display a login text banner? There's nothing obvious to me.

    Back in Fedora-15, there was a nice gui tool gconf-editor that handled these console login configurations in a straightforward way when gdm was the display manager. Even the command line tool gconftool-2 in earlier Fedoras seemed to handle this chore somewhat painlessly. Could there be something similar available for Fedora-18 with lightdm? Could new Fedora releases be moving ahead so quickly that some of these fundamental configuration capabilities are being forgotten or delayed?

  5. #5
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    Re: F18 lightdm login banner user list suppress

    Quote Originally Posted by bbmfedora

    There is a (not very human readable) xml configuration file in /usr/share/lightdm-gtk-greeter/greeter.ui. I wonder if something could be done with this file to display a login text banner? There's nothing obvious to me.
    I spent some time on this "intense" file a couple of weeks ago. You might have some luck by editing the section in red below.

    Replace/add text the [hostname] value to what you want displayed and see if that works.

    DISCLAIMER: I do not know if this work!

    Code:
    <object class="GtkLabel" id="hostname_label">
    <property name="name">hostname_label</property>
    <property name="visible">True</property>
    <property name="can_focus">False</property>
    <property name="label" comments="This is a placeholder string and ....">[hostname]</property>
    </object>
    There are a few things I have been able to get to work by spending time on this "impossible" file - like getting rid of Accessibility icon from the login window, changing ltr to rtl, etc. I haven't had time to tear this file down completely yet - so I am just playing around ... sigh!
    Last edited by nonamedotc; 29th January 2013 at 04:17 PM.

  6. #6
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    Re: F18 lightdm login banner user list suppress

    The glade3-3.8.3-1.fc18.x86_64 app opens the greeter-ui file and presumably will let you
    redesign it however you want. Looks like fun, actually.

    My gtk-greeter seems to be somewhat fragile to begin with - it is no longer displaying the Fedora
    logo here, and whether it will load the specified background image is running about 50/50 - when
    it doesn't work I get a pink and white speckled background.

    All the more reason to hack at it.

  7. #7
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    Re: F18 lightdm login banner user list suppress

    Quote Originally Posted by bbmfedora

    The problem of displaying security login banner text on the console login screen remains.
    Hi,

    just that I grasped this correctly, what you need is a text message on the console
    (e.g. after you press Ctrl+Alt+F2 in lightdm), right?

    Have you looked into /etc/issue ??

    That one does the trick for me. No need to fuzz around with the lightdm xml files.

    Speaking of lightdm xml files. Does someone know how to change the position of the
    greeter prompt somehow? Thanks to this thread here, I finally managed to get rid of the annoying
    user list in lightdm, without having to switch to kdm (which is somewhat oversized but at least
    themeable),
    Now, I'm just curious, if I could also change/modify the greeter box itself, to fit better with my
    background image. I suspect the solution is in /usr/share/lightdm-gtk-greeter - I already managed
    to resize the box by changing the width-request value in class GtkNotebook, but otherwise
    I'm stuck with that fairly complicated file. It's not really important, purely consmetic in fact,
    but maybe someone here's got a clue. Thanks.

  8. #8
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    Re: F18 lightdm login banner user list suppress

    Quote Originally Posted by JackC


    Speaking of lightdm xml files. Does someone know how to change the position of the
    greeter prompt somehow?
    I would also love to know how to set the position of the greeter! I have pretty much torn down the greeter.ui to pieces and nothing has worked for me with respect to positioning! Sigh!

    Another item I am curious about is moving the top bar. I was able to change the position of the reboot/shutdown icon easily in the xml file. But, I would like to move the top panel itself! No idea how to do that yet.

  9. #9
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    Re: F18 lightdm login banner user list suppress

    As mentioned above, you can open the greeter .xml file with glade and then
    move and resize the elements to your liking. The result would probably have to
    be re-integrated with the other parts of lightdm - the existing design appears to
    be "hard-wired" to some extent.

    I like lightdm except for the fact that it pulls in consolekit. As soon as I have time
    I hope to reconstruct how I got qingy working in F17, then it's adios lightdm and ck.

  10. #10
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    Re: F18 lightdm login banner user list suppress

    Well, the issue is that while editing it in glade does change the appearance of the greeter, it does not change the position.

    I can make the greeter big or small, square or rectangle, change the text here and there. But I cannot move the greeter left or right using glade or move it closer to the left edge of the screen - light the unity greeter's position in Ubuntu.

    glade does not help in that regard. ---- unless I am doing something wrong.

  11. #11
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    Re: F18 lightdm login banner user list suppress

    Looking at the greeter.ui in glade, there are 3 basic elements - the panel window, login window, and menubar.
    The login window does not seem to be positioned in any particular way inside the panel window, so it isn't
    immediately obvious how to change its location.

    Maybe you would have to establish a grid in the panel window, and then specify that you wanted the login
    window located at a particular spot in the grid. It's been a while since I did any GTK programming and I
    don't recall the specifics of how you pack widgets inside a window, particularly when you only have 1
    widget (the login window).

    It does appear doable for someone with the time and inclination.

    ---------- Post added at 09:34 PM ---------- Previous post was at 08:06 PM ----------

    Looking at the source in lightdm-gtk-greeter.c, it doesn't appear that you can change the location of
    the login window via any configuration settings. The login window is centered at line 1039 using the
    center_window function (at line 405).

    So you would have to patch the source, and add a routine to put the login window somewhere else.
    Still doable - but you would have to make sure your relocation worked on various types and sizes of
    displays, which is probably the reason it was done this way to begin with.
    Last edited by sonoran; 6th February 2013 at 10:07 PM.

  12. #12
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    Re: F18 lightdm login banner user list suppress

    Hi,

    thanks for looking into this. So I guess I'll forget about rearranging that login
    window for now (not much of a programmer). Just have to pick some background
    that's in harmony with the window being where it is.

    Still, an option where you could just configure an offset in pixels from the default
    position would have been nice. I don't see why that would be any problem with
    different screens either (default centred like now, offset at your own risk)
    - guess they just didn't care or think of it. Ever since I found the option to remove
    the user list, it's good enough for me.

  13. #13
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    Re: F18 lightdm login banner user list suppress

    Quote Originally Posted by sonoran

    [ ... ]

    [/COLOR]Looking at the source in lightdm-gtk-greeter.c, it doesn't appear that you can change the location of
    the login window via any configuration settings. The login window is centered at line 1039 using the
    center_window function (at line 405).

    So you would have to patch the source, and add a routine to put the login window somewhere else.
    Still doable - but you would have to make sure your relocation worked on various types and sizes of
    displays, which is probably the reason it was done this way to begin with.
    I did want to customize but I am not that desperate! Also, I am not sure if I have enough technical expertise though I can do a bit of coding in C and java.

    I will see if I can get slim login manager to work.

  14. #14
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    Re: F18 lightdm login banner user list suppress

    I'd like to be able to move the login window around too. In my case, it covers up an important part of my new background image on my laptop and I'd like to shift it to a more convenient location. I've entered a feature request at https://bugzilla.redhat.com/show_bug.cgi?id=918327

    Maybe if a few of you added "me too" comments, it might get some attention.
    Registered Linux user #470359 and permanently recovered BOFH.

    Any advice in this post is worth exactly what you paid for it.

  15. #15
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    Re: F18 lightdm login banner user list suppress

    Oh yeah! I never thought about that. But, wouldn't this be upstream's enhancement?

    ---------- Post added at 05:11 PM ---------- Previous post was at 05:11 PM ----------

    I guess I should have first read the bug report!
    Fedora 27 x86_64 XFCE - Sager | Intel Core i7 - 4810 MQ | NVIDIA GeForce GTX 860M | 16 GB RAM | 480 GB ADATA SSD |
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