In the subject of network security, before we get into action and get the necessary output, we need to have an in-depth understanding of theoretical issues because otherwise, we might be able to work with software and tools. Still, never we can dig deeper and become professional in network security. So in network security issues, first of all, we need to understand the theoretical fundamentals of network security fully.

Networks are becoming more and more popular every day. So much of our day to day jobs would not be possible without a network. Initially, the goal of network design was to transfer information quickly to the other in the shortest possible time. But expanding it and making it accessible to all and the knowledge of most network users has led some people with different motivations to take action to access information unknowingly or to block certain services. Or change their information. Therefore, the transfer of information became the goal of network design as soon as possible while maintaining its security.

Implementation of methods to ensure network security usually impedes the necessary operations that slow down the transmission of information. Therefore, network security works against the primary purpose of faster transfer of information and should be very subtle. In the 1980s, attacks were based on known vulnerabilities. In the 1990s, attacks were made based on network management deficiencies. From the year 2000 onwards, there is a new generation of attacks that operate automatically.

To be a domain expert, you first need to understand the basic concepts well. Those who want to get into the field of security are no exception. This book has tried to outline the basic concepts of security and has also raised the question of introducing some security software to drive interest in continuing on the path. In fact, in this book, you will be introduced to the basic concepts of security and the path you want to take.