Rule Set Based Access Control (RSBAC) is an open source security extension for current Linux kernels. It is based on the Generalized Framework for Access Control (GFAC) and provides a flexible system of access control implemented with the help of a kernel patch. All security relevant system calls are extended by security enforcement code. This code calls the central decision component, which in turn calls all active decision modules and generates a combined decision. This decision is then enforced by the system call extensions.