Specifications

Physical Security
The security threats we have considered so far relate to intangibles such as software, but you
should not neglect the physical security of your system. You need air conditioning, and protec-
tion against fire, people (both the clumsy and the criminal), power failure, and network failure.
Your system should be locked up securely. Depending on the scale of your operation, this
could mean a room, a cage, or a cupboard. Personnel who do not need access to this machine
room should not have it. Unauthorized people might deliberately or accidentally unplug cables
or attempt to bypass security mechanisms using a bootable disk.
Water sprinklers can do as much damage to electronics as a fire. In the past, halon fire suppres-
sion systems were used to avoid this problem. The production of halon is now banned under
the Montreal Protocol On Substances That Deplete The Ozone Layer, so new fire suppression
systems must use other, less harmful, alternatives such as argon or carbon dioxide. You can
read more about this at
http://epa.gov/ozone/title6/snap
Occasional brief power failures are a fact of life in most places. In locations with harsh
weather and above ground wires, long failures occur regularly. If the continuous operation of
your systems is important to you, you should invest in an uninterruptible power supply (UPS).
A UPS that will power a single machine for 10 minutes will cost less than $300 (U.S.).
Allowing for longer failures, or more equipment, can get expensive. Long power failures really
require a generator to run air conditioning as well as computers.
Like power failures, network outages of minutes or hours are out of your control and bound to
occur occasionally. If your network is vital, it makes sense to have connections to more than
one Internet service provider. It will cost more to have two connections, but should mean that,
in case of failure, you have reduced capacity rather than becoming invisible.
These sorts of issues are some of the reasons you might like to consider co-locating your
machines at a dedicated facility. Although one medium-sized business might not be able to jus-
tify a UPS that will run for more than a few minutes, multiple redundant network connections,
and fire suppression systems, a quality facility housing the machines of a hundred similar busi-
nesses can.
Next
In Chapter 14, we will look specifically at authentication--allowing your users to prove their
identity. We will look at a few different methods, including using PHP and MySQL to authen-
ticate your visitors.
E-commerce and Security
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