A security feature is added to the Wake On LAN packet protocol, and an extensible mechanism is provided allowing for other commands and options to be specified within the Wake On LAN packet. The protocol allows for signaling power management circuits in a host computer in response to messages received through a network interface. Logic coupled to the network interface detects a received network packet carrying a message from a source to the management circuits in the host computer. The logic includes security logic that is responsive to data in the packet to authenticate the source of the message, to accept the message and generate a signal to the management circuit in the host computer when the message passes authentication, and to discard the message when the message fails authentication. The message includes a message authentication code timestamp indicating a time at which the source produced the message and/or a random value token. The security logic includes resources to verify the message authentication code and to prevent re-use of the message.