**2. Security concept**

Security aims for achieving the protection of system information in order to preserve the data from manipulation and theft and to attain the availability, confidentiality, and integrity. It includes protection of hardware, software, information, and telecommunications [1].

Security is a term used to describe different states, such as lack of risks and threats situation, prevention of risks, or achieve confidence. Achieving security is required in many areas at the level of individuals and organisations. Ensuring security requires individuals with competence and experience, so the level of security varies from one organisation to another. To ensure better security for organisations and individuals, it is important for network users to use the systematic approach, which involves analysing, designing, implementing, and maintaining a required network security system [2].

There are many goals of security as illustrated below:


In order to gain illegitimate access, adversaries are capable of exploiting system weaknesses. As systems move out from homes and offices security to more settings in every place, security importance cannot be denied. It is essential to guarantee the hardware and software security of any system.
