This is something of a nightmare for smaller organisations that see a lot of guests, students or visitors. The licensing terms for the extension pack are quite expensive (minimum of 100 licenses at approx $60), and Oracle is fairly aggressive in tracking (by IP address) & pursuing companies that show as having downloaded the extension, even if that's only 1 or 2 people within the organisation. Oracle has chosen to provide the extension pack free of charge to individuals, yet will charge organisations, which makes sense for the when providing contracted support for large enterprises.

Therefore the extension pack is provided separately, for the purposes of revenue generation, maintenance, and management of licensing. So, the technologies are provided under proprietary licenses. A number of these functions are not open source and not covered under the GNU GPL. Now, Oracle also supplies the extension pack which provides useful additional functionality - virtual USB, Remote Desktop Protocol (VRDP) support, webcam passthrough, PXE boot ROM, PCI passthrough, ETC.

The base package of VirtualBox consists of open-source components and is licensed under the GNU General Public License. Created originally by Innotek, who were then purchased by SUN in 2008, now owned by Oracle.

What is virtualbox extension pack