Desktop

Disabling

If you are running a production deployment and don't need the desktop environment, you can disable the GUI altogether and boot in text mode:
http://askubuntu.com/questions/16371/how-do-i-disable-x-at-boot-time-so-that-the-system-boots-in-text-mode

Support

If you need to keep running the desktop environment and you're running XFCE, LXDE, or another desktop environment that is on the 3-year support cycle, you will most likely want to switch to a fully supported desktop environment until we're ready to move off of Ubuntu 14.04. We've prepared a package to make it easy to switch to Gnome Flashback (a lightweight environment similar to XFCE or LXDE).

Installing Gnome Flashback

Install the new securityonion-desktop-gnome package:

sudo apt update && sudo apt install securityonion-desktop-gnome

Converting to Gnome Flashback

After installing the securityonion-desktop-gnome package, you can now run the so-desktop-gnome script:

sudo so-desktop-gnome

The script will notify you that it is about to remove all XFCE packages and install Gnome Flashback. Press Enter to continue. When the script is finished, review all output for any error messages and then press Enter to reboot.

Resolution

Once you've rebooted and logged into the new Gnome Flashback session, you may want to change your display resolution:

• Click Applications → System Tools → Preferences → Displays
• Click the Resolution drop-down box and set your desired resolution
• If you don't see the Apply button, press Alt-F7 and then use your arrow keys to move the window until Apply is visible, then press Enter
• Click the Apply button