RC is Rclone’s remote control interface. It lets an administrator manage Rclone over HTTP or a similar control channel, including starting server-side features, changing settings, and observing or steering transfers. In practice, RC turns Rclone from a local sync tool into something that can be operated like a service.
This matters because any exposed control interface expands the attack surface. If RC is reachable by an attacker, they may be able to alter runtime behavior, launch serve modes, or influence authentication and backend-selection logic. In real defenses, RC should be bound to trusted networks, protected with strong authentication, and monitored for unexpected requests. Security teams also need to verify that the interface is actually disabled when it is not required, because even a small management API can become a high-value target once public exploits or proof-of-concept code appear.