virtualbox-guest-source 4.1.12-dfsg-2ubuntu0.9 (i386 binary) in ubuntu precise

 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 source code for the virtualbox guest addition kernel
 modules. The virtualbox-guest-utils package is also required in order to
 make use of these modules. Kernel sources or headers are required to compile
 these modules.