Device whitelisting is a security control that lets a system accept only approved hardware or storage devices. Anything not on the allowlist is blocked, even if it is physically connected. Administrators usually base approval on device type, serial number, vendor ID, or other identifiers.
It matters because many attacks begin with trusted-looking peripherals such as USB drives, external disks, or replacement media. In ATM and kiosk environments, whitelisting can help stop malware installation, unauthorized maintenance tools, and boot-media tampering. In practice, defenders combine it with cabinet locks, firmware checks, and logging so that only known service devices can interact with the machine.