To secure a network, it is important to identify the normal operating parameters so that you can recognize atypical variations from this baseline operational level. The first step toward minimizing the potential damage that may result from unauthorized access attempts is the detection and identification of an unauthorized intrusion. Intrusion detection requires a detailed understanding of all operational aspects of the network, along with a means to identify variations and bring these changes to the attention of the proper responsible parties. Auditing is done to protect the validity and reliability of organizational information and systems. As a security professional, you can audit a vast amount of data. Auditing can create a large repository of information that has to be filtered through.

The concept of security within the network environment includes aspects drawn from all operating systems, application software packages, hardware solutions, and networking configurations present within the network to be secured, and from within any network-sharing connectivity directly or indirectly with the network to be secured. For the Security+ exam, you need to develop the broadest set of skills possible, gaining experience from the most specific to the most general of security concepts. This chapter focuses on access control mechanisms and methods for secure network authentication and physical access.

The network infrastructure is subject to myriad internal and external attacks through services, protocols, and open ports. It is imperative that you understand how to eliminate nonessential services and protocols, especially if the network has been in existence for some period of time and some services are no longer needed or have been forgotten. To stop many would-be attackers, you must understand the different types of attacks that can happen, along with how to implement a network design, components, and tools that can protect the infrastructure. Be sure to give yourself plenty of time to review all of these concepts.