In order to create a new base box, we need to download a copy of the operating system we want to use (we will use Ubuntu Server Version 13.04 64-bit from http://releases.ubuntu.com/raring/). We then need to use VirtualBox to create a virtual machine, powered by the operating system we have downloaded. Next, we need to configure the virtual machine for Vagrant. Finally, we need to export the virtual machine into a Vagrant base box.
Tip
You can also use other distributions of Linux or even Windows if you wish. Specifics will vary with the operating system used, so you will need to consult the relevant documentation.
The requirements for a new base box are detailed on the Vagrant website (https://docs.vagrantup.com/v2/boxes/base.html).