This chapter discussed some of the basics of security. Planning for security can be a complex process, but having a security policy simplifies it. A security policy is one of the most important tools that you will use to design and implement a security solution.

Causes of security problems include weaknesses in policy definitions, computer technologies, and equipment configurations. Security threats can come from internal as well as external sources and are either structured or unstructured. Most security threats originate inside your network.

Security threats are categorized as a reconnaissance, DoS, or access attack. In a reconnaissance attack, the hacker it trying to learn information about your network, including its weaknesses. The hacker then uses this information to implement a DoS or access attack.

Cisco has developed a four-step security wheel to help deal with the implementation and maintenance of a security solution. Security is a never-ending process, so you will be repeating the four steps quite often.

Next up is Chapter 2, which discusses what a firewall is, the types of firewalls, and how to design networks with firewalls.