TABLE OF CONTENTS The physical layer (layer 1) sits at the bottom of the Open Systems Interconnect (OSI) model, and is designed to transmit bit streams using electric signals, lights, or radio transmissions. For this chapter, the definition of the physical layer is expanded to include all physical things.True security means building defense-in-depth, which is used in this chapter to expand the OSI concept on a much broader scale. We begin by looking at some of the methods used to defend the physical environment, including common concepts such as lights, locks, and guards. Next, we examine the attacks on the physical layer, which are different from attacks on all of the other layers, therefore requiring different defensive techniques and skills. We believe that physical security should encompass the wiring used to connect systems as well as the system hardware, supporting services, employees, and any other physical assets.
This section examines ways to defend the physical layer. Physical security is the point at which protection should begin. How much physical security you need depends on your situation, assets, and budget.These security controls have three primary goals:
Deter Two methods used to deter intruders are security lighting and Beware of Dog signs.
Delay Some of the techniques used to delay an intruder include fences, gates, locks, access controls, and mantraps.
Detect Two systems used to detect intruders are intrusion detection systems
(IDSes) and alarms.
Physical security (layer 1) should be viewed differently than the...
