This book is designed for individuals who need to better understand the
functionality of security tools. Its objective is to help guide those individuals
in learning when and how specific tools should be deployed and what any of
the tools’ specific limitations are. This book is for you if any of the following
are true:

• You want to learn more about specific security tools.
• You lack hands-on experience in using security tools.
• You want to get the skills needed to advance at work or move into a new position.
• You love to tinker or expand your skills with computer software and hardware.
• You are studying for a certification and want to gain additional skills.

You may be wondering what security is. Security typically is defined by
three core concepts: confidentiality, integrity, and availability. There is also
the question as to how much security is enough. Some might say that you can
never have enough security, yet in reality it is about balancing the value of the
asset and the cost of protection. One thing that is agreed upon about security
is the value of defense in depth. Simply stated, security controls should be
built in layers. For example, renaming the administrator account is a good
idea, but so too is restricting access to the account, as well as adding complex
passwords and performing periodic audits of the log files.
Because no two networks are the same, and because they change over time,
it is impossible to come upwith a one-size-fits-all list of hardware and software
that will do the job for you. Networks serve the enterprise that owns them.
The enterprise necessarily changes over time, too. In addition, the scale of
operation impacts security considerations. If you pursue a career as a security
consultant, your goals (and inevitably your needs) will differ if you decide
to work for a large multinational corporation (and even differ depending on
the type of industry) or if your interests lie primarily with small office/home
office (SOHO) or small business. Clearly, a whole spectrum of possibilities
exists here.