install virtualbox on ubuntu 16.04

sudo sh -c 'echo "deb http://download.virtualbox.org/virtualbox/debian xenial 

contrib" >> /etc/apt/sources.list.d/virtualbox.list'

wget -q https://www.virtualbox.org/download/oracle_vbox_2016.asc -O- | sudo apt-key add -

sudo apt update

sudo apt install virtualbox-5.1

출처: http://ubuntuhandbook.org/index.php/2016/07/virtualbox-5-1-released/