Data and Cabling Security for Prevention

Written by Julianus Yu

Your network cables carry all the data that crosses your network. If the data your cables carry is sensitive and should not be viewed by just anyone, you may need to take extra steps when designing and installing your cabling system to ensure that the data stays where it belongs: inside the cables. The level of protection you employ depends on how sensitive the data is and how serious a security breach could be. Cabling security measures can range from the simple to the absurdly complex.

Two ways to prevent data from being intercepted are;

EM (Electromagnetic) Transmission Regulation
You should know that the pattern of the magnetic field produced by any current-carrying conductor matches the pattern of the signals being transmitted. Based on this concept, devices exist that can be placed around a cable to intercept these magnetic signals and turn them back into electrical signals that can be sent to another (unwanted) location. This process is known as EM signal interception. Because the devices pick up the magnetic signals surrounding the cable, they are said to be noninvasive.

Susceptibility to EM signal interception can be minimized by using shielded cables or by encasing all cabling runs from source to destination in a grounded metal conduit. These shielding methods reduce the amount of stray EM signals.

Tapping Prevention
Some tapping devices are invasive and will actually puncture the outer jacket of a cable, or the insulation of individual wires, and touch the metal inner conductor to intercept all signals sent along that conductor. Of course, taps can be applied at the cross-connects if security access to your equipment rooms and telecommunications rooms is lax.

To prevent taps, the best course of action is to install the cables in metal conduit or to use armored cable, where practical. Grounding of the metal conduit will provide protection from both EM and invasive taps but not from taps at the cross-connect. When not practical, otherwise securing the cables can make tapping much more difficult. If the person trying to tap your communications can’t get to your cables, they can’t tap them. So you must install cables in secure locations and restrict access to them by locking the cabling closets. Remember: If you don’t have physical security, you don’t have network security.