A command link is the communication path through which an operator or control system sends instructions to a vehicle or device. It may use radio, wired connections, or network protocols, depending on the system. Command links are distinct from telemetry paths, which carry status and performance data back to operators, though the same connection can support both directions.
In cyber security, protecting a command link helps prevent unauthorized control, tampering, or disruption. Attackers may try to intercept or spoof commands, exploit weak authentication, or block communications. Defenses include strong authentication and encryption, access controls, secure key management, and checks that reject invalid or unexpected commands. For remote or autonomous equipment, resilient communication and safe behavior during link loss are also important, since a failed or compromised connection can affect operations.