Introduction+to+Computer+Security_Part7 - 15. Physical and...

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15. Physical and Environmental Security 169 Life Safety It is important to understand that the objectives of physical access controls may be in conflict with those of life safety . Simply stated, life safety focuses on providing easy exit from a facility, particularly in an emergency, while physical security strives to control entry. In general, life safety must be given first consideration, but it is usually possible to achieve an effective balance between the two goals. For example, it is often possible to equip emergency exit doors with a time delay. When one pushes on the panic bar, a loud alarm sounds, and the door is released after a brief delay. The expectation is that people will be deterred from using such exits improperly, but will not be significantly endangered during an emergency evacuation. There are many types of physical access controls, including badges, memory cards, guards, keys, true-floor-to-true-ceiling wall construction, fences, and locks. 15.1 Physical Access Controls Physical access controls restrict the entry and exit of personnel (and often equipment and media) from an area, such as an office building, suite, data center, or room containing a LAN server. The controls over physical access to the elements of a system can include controlled areas, barriers that isolate each area, entry points in the barriers, and screening measures at each of the entry points. In addition, staff members who work in a restricted area serve an important role in providing physical security, as they can be trained to challenge people they do not recognize. Physical access controls should address not only the area containing system hardware, but also locations of wiring used to connect elements of the system, the electric power service, the air conditioning and heating plant, telephone and data lines, backup media and source documents, and any other elements required system's operation. This means that all the areas in the building(s) that contain system elements must be identified. It is also important to review the effectiveness of physical access controls in each area, both during normal business hours, and at other times particularly when an area may be unoccupied. Effectiveness depends on both the characteristics of the control devices used (e.g., keycard-controlled doors) and the implementation and operation. Statements to the effect that "only authorized persons may enter this area" are not particularly effective. Organizations should determine whether intruders can easily defeat the controls, the extent to which strangers are challenged, and the effectiveness of other control procedures. Factors like these modify the effectiveness of physical controls. The feasibility of surreptitious entry also needs to be considered.
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Introduction+to+Computer+Security_Part7 - 15. Physical and...

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