I-Cluster [1] is an HP Laboratories Grenoble initiative in collaboration with the ID-IMAG laboratory of INRIA Rh?ne-Alpes. The aim of this research programme is to develop a framework of tools that transparently take advantage of unused network resources and federate them to crystallize into specific virtual functions such as supercomputing. To be more precise, I-Cluster enables automatic real-time analysis of the availability, configuration and workload of machines on an intranet. When instantiation of a supercomputing function is carried out by a user, I-Cluster determines the most appropriate set of machines for carrying out this function, allocates the machines into a virtual cluster and then starts execution of the function. To obtain this result, I-Cluster possesses a "sandbox" on each machine on the intranet, which is transparent to the user, and that enables use of the computing resources of these machines during their idle periods while securely protecting user data and jobs. This document presents the sandbox developed for I-Cluster and its features.