Regardless of any of this, the concept is based on a simple premise: the six-sided cube. If one has something to protect, let’s say a diamond ring, arguably the best way to protect it would be to put it inside a steel cube.  So, if one cut square steel plates measuring 1 foot on each side and welded these into a box after which the diamond ring was placed inside and the sixth side welded firmly in place, one could argue that a very good protection mechanism had been created. Of course, the box can be stolen or burnt, damaging the contents inside but for a moment let’s only consider the security of the perimeter.

An obvious problem is created by what has just been described: there is no access to the asset inside. Therefore, an opening must be created which can be closed and secured thereafter. Hence, we build a door with hinges and install a lock. This immediately creates a vulnerability and we must assure ourselves that the hinges and locks are secure. This is the domain of the security professional.

When one thinks of securing anything, one should think in terms of the security perimeter, i.e.: the six-sided box. If we are securing a building, our house let’s say, it has six sides which must be considered.  Generally, the vertical sides have portals secured by doors and windows which must themselves be secured. The roof may have skylights or other openings which must be considered. Preparations in the envelope for mechanical equipment could be of concern. And the actual composition of the building envelope must be strong enough to resist penetration.

Another common security perimeter is the fence.  A fence does not create our six-sided perimeter: we are missing the sixth side. What can we do to achieve security when one of the sides of the cube is missing? We generally add technology and we may add human surveillance. Technology can come in many forms such as cameras, fence monitoring, motion detection, etc. When the asset we are trying to protect is of high-value, we will often add human surveillance in the form of patrolling guards.

Securing assets using a fence is very difficult. Even high fences with barbed wire toppers pose little challenge to determined attackers. The American military has tested various kinds of fencing to determine the length of time it would take an attacker to go through a fence or over it. The typical example is the chain-link fence, 2.2-metre in height, with a 0.3-metre barbed wire topper protruding outward. In all of their tests, two men with no tools typically got over the fence in 4 to 5 seconds.

Then, what can be done to create a real security perimeter for something which must be protected outside? The author has seen various applications at high security facilities and generally the approach is to create a double barrier by duplicating the fence line which sandwiches a no-man’s zone. In this case, moving inward, the outside fence is a significant height and protected using technology. This is followed by a 10-meter space which is usually equipped with ground sensors or microwave beams followed by a second, technology-equipped fence. Creating a barrier in this way gives a security force time to respond to anyone trying to penetrate it.

Another use for the perimeter fence is as a second layer perimeter. It is designed to give warning of an attack. Even a number of layers of fencing can be used to provide warning of an attack. A good example of this is a prison where an outer fence is controlled electronically and via a portal gate. As one moves in towards the asset, one may encounter a brick or stone wall equipped with human observation and technology.  Inside the walls, buildings are used as perimeters to protect valuable assets. And, finally, the interior spaces are divided into access-controlled spaces to house prisoners and other assets.

It is beyond the scope of this article to discuss information technology security; however, the very same principles are applied when securing a network. “Edge appliances” create secure perimeters containing firewalls and intrusion detection features similar to the sensors we would find on a chain-link fence. The concept is the same: early warning.

We have seen many organizations trying to create security without having this basic understanding. Security professionals receive this knowledge during their training and they use this approach to achieve security for valuable assets. While some organizations believe that anyone can create security by locking doors and windows and installing alarms and CCTV cameras, this could be a waste of time unless these foundation concepts are understood.

One last word of caution: all security is based on security perimeters but all security perimeters are not linear. High-rise buildings are the most complicated because they have so many different portals on so many levels. Garages, patios, lobbies, and perimeter doors create varying complexity for perimeter security. However, the adage: you’re only as strong as the weakest link, applies powerfully to security perimeters. When doing an assessment of your perimeter, the strong steel door you have out front may be very effective but the hollow wooden door at the side will lead to your undoing.  The seven-foot fence with barbed-wire topper may be effective but if it is only five feet at the rear, then the desired results have been compromised.  This makes it important to understand how security perimeters must be continuous and how all components should be of equal strength. Maybe it’s time for you to look at your security from this point of view.