Why install guest additions for you Ubuntu Server?

VirtualBox Guest Additions can greatly increase the performance of your Ubuntu Virtual Machine and also enable some useful features like:

• Mouse pointer integration - Allow to Move mouse pointer between the host computer and the Ubuntu virtual machine.
• Folder Sharing - Share Folders between the host and the virtual machine.
• Shared Clipboard - Share clipboard between the host and virtual machine.
• Seamless mode - Allow to run the Virtual Machine in the seamless mode.

To Install Guest Additions

Once the host has booted, click Devices | Insert Guest Additions CD Image. Log in to your guest server. Mount the CD-ROM with

sudo mount /dev/cdrom /media/cdrom.

(If you get a /media/cdrom does not exist error then you will need to create the mount point)

mkdir /media/cdrom

sudo mount -t auto /dev/cdrom /media/cdrom

Change into the mounted directory with

cd /media/cdrom

Install necessary build tools and build dependencies with

sudo apt-get install -y dkms build-essential linux-headers-generic linux-headers-$(uname -r).

Change to the root user with

sudo su -

Install the Guest Additions package with

./VBoxLinuxAdditions.run.

Allow the installation to complete. You may see an error stating that the installer couldn't find the X.Org or XFree86 Window System—that's okay, because it doesn't exist on this host.

Reboot your machine and the Guest Additions will be working. You should see a bit of a performance increase, as well as the extra features (shared clipboard, shared folders, and more) awarded by this installation.