How to Install VirtualBox Guest Additions in Debian 9 Virtual Machine

VirtualBox guest additions offer the following capabilities:

Enable users to seamlessly move mouse pointer between host and guest. Allow guest OS to have read and write access to hard drives on the host OS. Power up the graphics ability of your guest machine. The screen resolution of guest machine can be automatically adjusted and 3D graphics can be accelerated. Enable bidirectional shared clipboard between host and guest.

Boot up your Debian 9 virtual machine. Then switch to root with the following command:

su -

Next, update software.

apt update

apt upgrade

If a new Linux kernel is installed in the upgrade process, then you need to reboot Debian 9 VM. After that, run the following command to install required packages for building kernel modules.

apt install build-essential module-assistant dkms

Once the above packages are installed, prepare your Debian 9 system to build kernel module, which is done with the command below.

m-a prepare

Then in the VirtualBox window, select Devices > Insert Guest Additions CD image.

You will be asked if you want to run the software. Select Run.

If your host OS doesn’t have the guest additions CD image, then it will ask you to click a button to download the CD image onto the host machine.You can manually download it from http://download.virtualbox.org/virtualbox.

Ubuntu-based Linux distro can also download the CD image with the following command (with root privilege).

apt-get install virtualbox-guest-additions-iso

Once you click the Run button, the CD image is mounted at media/cdrom directory. Under media/cdrom directory there’s a shell script named VboxLinuxAdditions.run. Run this script (with root privilege).

sh /media/cdrom/VBoxLinuxAdditions.run

Once guest additions is installed, restart your Debian 9 VM.

shutdown -r now

Now the resizeable display should be working and the resolution of Debian 9 VM will adjust with the size of VirtulBox window. You can press right Ctrl and F keyboard shortcut to enter full-screen mode. You can now also configure shared folder and bidirectional shared clipboard.