In this manuscript we describe the implementation of a digital twin for industrial networks. The aim is to provide a playground for cyber-security analysis and validation without the risk of interfering to any extent with the real cyber-physical system and its environment. The proposed implementation methodology provides a very high degree of automation, following the telecom-oriented NFV-MANO approach, and shows that different network topologies may be activated in a matter of just a few minutes. Each topology may then be used as a sort of cyber-range for the experimentation of possible attacks and validation of related countermeasures.