The critical infrastructures of our society are in the process of being modernized. Most significantly impacted are the industrial control systems through replacement of old electromechanical systems with advanced computing and communication technologies. This modernization has introduced new vulnerabilities to those infrastructures. Securing critical infrastructures is a challenging research problem, as these control systems were not designed with security in mind. This paper presents a testbed designed to study and simulate the various available techniques for securing and protecting Supervisory Control and Data Acquisition (SCADA) systems against a wide range of cyber attacks. The testbed is also used to evaluate the detection rate, false alerts and effectiveness of the protection techniques. We present preliminary results on using the testbed to detect a selected set of cyber attacks and the impact of the protection techniques on the operations of the system.