Critical infrastructures such as the power grid are essentially physical processes controlled by computers connected by networks. They're usually as vulnerable as any other interconnected computer system, but their failure has a high socioeconomic impact. The Critical Utility Infrastructural Resilience (Crutial) project designed an information switch (CIS) to protect these infrastructures. These devices help ensure that incoming and outgoing traffic satisfies the security policy of an infrastructure in face of cyberattacks. A CIS isn't a firewall, but a distributed protection device based on a sophisticated access control model. Furthermore, a CIS is intrusion-tolerant and self-healing, seeking perpetual unattended correct operation.