Abstract: A network security appliance that provides security to devices in industrial environments by transparently bridging traffic to the endpoint device. The security appliance securely communicates with a management server for receiving configuration data for operation of security modules in the appliance by encrypted communications. The security appliance utilizes the network address of the industrial device when communicating with a management server and is addressed by the management server using the address of one of the protected devices associated with the appliance. Learned device characteristics are provided by the appliance to the management server which tailors software and security rules to specific network vulnerabilities of the device and control protocol. The security appliance sends periodic heartbeat messages to the management server using the network address of the device.