VirtualBox Extension Pack provides free new features to your VirtualBox virtualization app.
VirtualBox Extension Pack includes a USB (EHCI) controller that gives you the ability to obtain better performance from your USB devices. You also gain access to VirtualBox Remote Desktop Protocol (VDRP) support that permits controlling a virtual machine from a separate PC. There is an online manual detailing usage and FAQ.
VirtualBox Extension Pack also includes support for remote PC booting via Intel PXE boot ROM emulation (including support for the E1000 network card).
Oracle VM VirtualBox extension packages have a .vbox-extpack file name extension; to install the extension, you will double-click on the package file, and a Network Operations Manager window is shown to guide you through the required steps.
To view the extension packs that are currently installed, start the VirtualBox Manager. From the File menu, select Preferences. In the window that displays, go to the Extensions category. This category shows you the extensions which are currently installed and enables you to remove a package or add a new package.