Yes, there are extensions for VirtualBox, but they're not available for current version of VirtualBox. The Old Builds page provide a way to download these extensions. They're in .vbox-extpack file format. Double click the file you've downloaded from the OldBuilds page and VirtualBox will prompt you to install them. The extensions are used to increase VirtualBox functionality and they're created for:
- The virtual USB 2.0 (EHCI) device;
- The virtual USB 3.0 (xHCI) device;
- VirtualBox Remote Desktop Protocol (VRDP) support;
- Host webcam passthrough;
- Intel PXE boot ROM.
- Experimental support for PCI passthrough on Linux hosts;
- Disk image encryption with AES algorithm;
Old Builds page: https://www.virtualbox.org/wiki/Download_Old_Builds_5_0
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