ABSTRACT
With the introduction of computers and the internet, the world witnessed a rapid change in the mode of business. Currently, almost all organizations-ranging from the government to small private enterprises-have either largely computerized their state of affairs or are in the process of doing so. Thus, modern offi ces have become synonymous with sets of workstations connected to each other and sharing information in real time. With the number of processing demands from customers running an all-time high, these networks have become quite complex in nature-ranging from LANs and Edge Networks to WANs. Note, however, that the organization employees often need to connect to the internet for running their daily chores, and the organizations themselves also need to connect to the internet to have an online presence. But the moment the internet is connected to the internal network, the latter becomes subject to a wide range of vulnerabilities and network security threats from external users. To protect the internal network, the servers and the organizational data from such external threats, a new application known as the “firewall” was introduced. Like its counterpart in building construction, a fi rewall protects the internal network from the “fi re” of external threats coming from the internet. Along with firewalls, intrusion detection
and prevention systems also play a key role in deterring or removing external attacks. This chapter presents a fi rst-hand overview to such systems.
