Re: Fiber optic vampire taps

I believe, if my memory isn't failing me, that I read mention of this a few years back; perhaps research in AT&T? The cladding does indeed have to be stripped clear, baring the naked fiber. Then the fiber is carefully, delicately bent past its minimum rated radius of curvature, in a little jig that holds a receiving fiber positioned to pick up the light as it leaks out.

I suspect impedence matching would be tough, so I suspect the end result would have a very low signal level. I don't know whether some sort of optical amplifier, or perhaps custom NIC hardware with a higher-than-usual sensitivity listening device, would be required to actually decode the tapped the light.

I've never heard of these gizmos being available commercially.

This situation is why many regard fiber as intrinsically fairly secure.

In principle, a detector could report on received light levels with enough sensitivity to detect a successful attack on the fiber. Another grade of kit I've not heard of for sale.

Perhaps it would be easier to do your own manual attenuation; perhaps deliberately coil a little of the fiber at one end, gently tightening the coil (past minimum recommended radius of curvature) until the attenuation causes actual packet loss, then backing off slightly; if you had a fiber that just _barely_ didn't work, any attempt to tap it would push it badly into packet loss, so normal network monitoring should be able to detect a tapping attempt.

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The traditional solution, when you are concerned about such, is to armor the whole fiber run in pressurized conduit, set alarms to go off if the conduit pressure changes, then post guards keeping a close enough watch to prevent someone from setting up a pressure box to set up their tap.

-Bennett