1. Download and install Oracle’s public key.

danesh@python:~$ wget -q http://download.virtualbox.org/virtualbox/debian/oracle_vbox.asc -O- | sudo apt-key add -

  1. Create a repo file for Virtualbox

danesh@python:~$ sudo -s  echo "deb http://download.virtualbox.org/virtualbox/debian precise contrib" >> ~/virtualbox.list

danesh@python:~$ sudo mv ~/virtualbox.list /etc/apt/sources.list.d/

  1. Install Virtualbox

danesh@python:~$ sudo apt-get update

danesh@python:~$ sudo apt-get install dkms

danesh@python:~$ sudo apt-get install virtualbox-4.1

Enjoy.