Network device authentication based on hashing content of sequential messages

A method, performed by an authentication processor of a first network device, includes receiving a first message through a network interface circuit from a second network device. The first message contains a first data unit to be operated upon by the first network device. A second message is received through the network interface circuit from the second network device. The second message contains a reported authentication token for the second network device and a second data unit to be operated upon by the first network device. The first message is received before receipt of the second message. A check authentication token is generated based on hashing the first data unit. A command that controls operation of the first network device is selectively performed on the second data unit based on whether the check authentication token matches the reported authentication token.