Edit: also works with Ubuntu Server 16.04
1 Install dkms. From the guest run:
sudo apt-get install dkms
- From the VirtualBox VM window menu select:
Devices --> Insert Guest Additions CD image...
- Use blkid to identify the CD-ROM device. From the guest run:
sudo blkid
One of the lines in the output should look like this:
/dev/sr0: LABEL="VBOXADDITIONS_4.3.16_95972" TYPE="iso9660"
The first part (/dev/sr0) is the name of the CD-ROM device.
- Mount the CD (replace /dev/sr0 by the device name found above):
sudo mount /dev/sr0 /media/cdrom/
- Run the Guest Additions installer:
sudo /media/cdrom/VBoxLinuxAdditions.run
- Reboot the guest.