We present a control-theoretic approach to achieve Cyber-Physical Systems (CPS) resilient designs. We assume situations in which the CPS must maintain the correct operation of a set of crucial functionalities despite ongoing adversarial misbehavior. The approach is based on a moving target defense paradigm, driven by a linear switching of state-space matrices, and applied at both the physical and network layers of a networked-control system. We show that the final system maintains stability. We also evaluate, via simulation, a step-by-step procedure that takes a transfer function, representing the dynamics of the physical process. As a result, we obtain a resilient CPS design structured around a topology of decentralized controllers. Results show that the obtained approach is both innovative and promising.