A mobile computing device of a user transmits a digital certificate to a server computing device over a non-networking connection established with the server computing device. The digital certificate identifies the user, a particular server computing device, a validity period in which the digital certificate is valid, and a list of actions that the user is permitted to perform on the particular server computing device during the validity period. The server computing device authenticates the digital certificate, such as by determining whether a current time is within the validity period and whether the particular server computing device is the server computing device. When authentication is successful, the user can perform any action of the list of actions, including an action to power off the service computing device. The non-networking connection is such that the user is not provided a user account and a password to access the server computing device.
