Notify of the system security classification

You can set up an overlay notification that displays a predefined security classification message before or during login.

About this task

The gnome-shell-extension-heads-up-display extension shows a predefined security classification message in an overlay banner. Depending on your configuration, the notification can appear at the login screen, after logging in, on the lock screen, or after a longer period with no user activity.

You can always clear the notification when it is displayed. This approach differs from a permanent classification banner, which remains visible on the screen.

Procedure

  1. Install the gnome-shell-extension-heads-up-display package: 
    # dnf install gnome-shell-extension-heads-up-display
  2. Create the 99-hud-message file at either of the following locations:
    • To configure a notification at the login screen, create /etc/dconf/db/gdm.d/99-hud-message.
    • To configure a notification in the user session, create /etc/dconf/db/local.d/99-hud-message.
  3. Enter the following configuration in the created file: 
    [org/gnome/shell]
enabled-extensions=['heads-up-display@gnome-shell-extensions.gcampax.github.com']

[org/gnome/shell/extensions/heads-up-display]
message-heading="<security_classification_title>"
message-body="<security_classification_description>"
# The following options control when the notification appears:
show-when-locked=true
show-when-unlocking=true
show-when-unlocked=true

    Replace the following values with text that describes the security classification of your system:

    Security classification title
    A short heading that identifies the security classification.
    Security classification description
    A longer message that provides additional details, such as references to various guidelines.
    Warning

    This configuration overrides similar configuration files that also enable an extension, such as Enabling system security classification banners.

    To enable multiple extensions, specify all of them in the enabled-extensions list. For example:

    enabled-extensions=['heads-up-display@gnome-shell-extensions.gcampax.github.com', 'classification-banner@gnome-shell-extensions.gcampax.github.com']
  4. Update the dconf database: 
    # dconf update
  5. Reboot the system.
  • If the notifications are not displayed for an existing user, log in as the user and enable the Heads-up display message extension using the Extensions application.