The proper way to install virtualbox on Ubuntu Linux

For Ubuntu 14.04

sudo sh -c 'echo "deb http://download.virtualbox.org/virtualbox/debian trusty contrib" >> /etc/apt/sources.list.d/virtualbox.list'

For Ubuntu 13.10

sudo sh -c 'echo "deb http://download.virtualbox.org/virtualbox/debian saucy contrib" >> /etc/apt/sources.list.d/virtualbox.list'

For Ubuntu 13.04

sudo sh -c 'echo "deb http://download.virtualbox.org/virtualbox/debian raring contrib" >> /etc/apt/sources.list.d/virtualbox.list'

For Ubuntu 12.10

sudo sh -c 'echo "deb http://download.virtualbox.org/virtualbox/debian quantal contrib" >> /etc/apt/sources.list.d/virtualbox.list'

For Ubuntu 12.04

sudo sh -c 'echo "deb http://download.virtualbox.org/virtualbox/debian precise contrib" >> /etc/apt/sources.list.d/virtualbox.list'

For Ubuntu 11.10

sudo sh -c 'echo "deb http://download.virtualbox.org/virtualbox/debian oneiric contrib" >> /etc/apt/sources.list.d/virtualbox.list'

For Ubuntu 11.04

sudo sh -c 'echo "deb http://download.virtualbox.org/virtualbox/debian natty contrib" >> /etc/apt/sources.list.d/virtualbox.list'

Once you added the repo using the above command, Update your repository.

sudo apt-get update && sudo apt-get install -y virtualbox-4.3