sudo apt-get install openssh-server

sudo cp /etc/ssh/sshd_config /etc/ssh/sshd_config.factory-defaults sudo chmod a-w /etc/ssh/sshd_config.factory-defaults

sudo nano /etc/ssh/sshd_config # change auth mode if needed

sudo systemctl restart ssh sudo shutdown -P now

http://askubuntu.com/questions/64915/how-do-i-install-ubuntu-on-a-virtualbox-client-from-an-iso-image