virtualbox-guest-x11 5.0.18-dfsg-1ubuntu1 (amd64 binary) in ubuntu xenial

 VirtualBox is a free x86 virtualization solution allowing a wide range
 of x86 operating systems such as Windows, DOS, BSD or Linux to run on a
 Linux system.
 .
 This package provides the X11 guest utilities for VirtualBox. These utilities
 are meant to be run inside the virtual machine.
 They provide closer integration and improve the interactive performance.