A data processing device includes primary resources, an out-of-band manager operably connected to the primary resources via an always-on in-band connection, and an authentication engine. The authentication engine obtains, via the always-on in-band connection, an operation request and an authentication token corresponding to the operation request; in response to obtaining the authentication token: obtains a list of authorized operations using the authentication token; makes a determination that an operation indicated by the operation request is allowable based on the list of authorized operations; and performs the operation based on the determination.