Local area network electronic perimeter security

A secure electronic local area network comprising:

• a local area network asset connected to an external network;
• means connected to said local area network asset to detect the presence of extraneous electronic circuitry placed onto the physical wiring which were not originally designed as part of the electronic circuitry of that local area network, said extraneous electronic circuitry originating from said external network;
• means connected to said local area network to report said presence of extraneous electronic circuitry;
• and
• means to take action against said extraneous electronic circuitry, wherein said means to take action further comprises:
• means to detect intruder(s) presence through the application of Kirchoff's theorem, Thevenin's equivalent theorem and Norton's theorem, combined with the fact that the rise and fall of the characteristic time constant, τ, as measured by using circuit values including voltage and current, in response to a transient that is asymptotic and the values begin to rapidly change soon after the transient is applied and settles down overtime, wherein the value τ is reflective of the network signature, including the attached nodes at any time.