Detection of unauthorized entities in communication systems

A network element comprising:

• a memory;
• and
• a processor communicatively coupled to the memory, the processor configured to:
• obtain a secret string;
• generate a random number;
• compute a first cryptographic result, the first cryptographic result based on a cryptographic function, the secret string, and the random number;
• attempt to transmit, in a first packet that includes the random number to a second network element using a layer 2 packet terminating protocol;
• receive, within a configured time, a second packet including a second cryptographic result;
• and
• terminate transmission to the second network element when a second cryptographic result is different from the first cryptographic result.

A network interface comprising:

• a first network element;
• and
• a second network element communicatively coupled to the first network element, the first network element configured to:
• obtain a secret string;
• generate a random number;
• compute a first cryptographic result, the first cryptographic result based on a cryptographic function, the secret string, and the random number;
• attempt to transmit a first packet that includes the random number to the second network element using a layer 2 packet terminating protocol;
• receive, within a configured time, a second packet including a second cryptographic result;
• and
• terminate transmission with the second network element when the second cryptographic result is different from the first cryptographic result.