Abstract: A mechanism for ensuring the physical location of data processing devices as a security check is provided. With this mechanism, security data is transmitted to data processing devices via an electrical network and is used to perform a security check to determine if the data processing device may operate. The data processing devices may be limited such that they may only power-up, boot-up, or remain operational when they are coupled to the electrical network. Thus, they must be physically located such that they may gain access to the electrical network. In addition, a security check may be used to control which data processing devices may communicate data packets with one another over the data network. When a data packet is received by a data processing device, security data in the data packet is compared against a local history of security data received by the recipient of the data packet via the electrical network.