Proximity-based management of a computing device

Techniques for enabling a user computing device to manage a controlled device only when the user computer device is physically proximate to the controlled device are disclosed. The controlled device repeatedly provides codes that change at select times and the user computing device sends the last received or captured code back to the controlled device. The user computing device is enabled to manage the controlled device when the most recent code sent by the user computing device matches one or more codes most recently provided by the controlled device. Additionally or alternatively, the user computing device is enabled to manage the controlled device when the user and controlled devices connect to the same access point. A technique for enabling the user computing device to share, mirror, or cast a screen on the user computing device onto a display of the controlled device is also disclosed.