In the earlier section, we spent considerable time understanding NIDS. This has built a solid foundation, which we will find useful when moving on toward understanding NIPS.

Unlike a NIDS, which is a passive system, a NIPS is an active system that monitors network traffic and takes immediate preemptive action when a threat is detected. Intrusions are normally followed very quickly by vulnerability exploits. These are usually in the form of a malicious injection of data into an application or service with the objective of interrupting and gaining control of a machine or application. This could result in a denial of service (disabling applications or services), misusing existing privileges (rights and permissions) or escalating them for misuse, and gaining control of systems or resources.

In the information security world, most exploits come with an expiration date. This is because the moment an exploit has been identified, software vendors...