Nowadays, a big challenge is how to protect information from unwanted accesses. It constitutes a big challenge when we have different ways to access data. That is, a lot of information today travels through networks and our challenge today is to guarantee that traveled information should be secret that is not divulged by intruders. There are many different ways to assure that information being transmitted through a network is secret. In this paper, after we have shown in Section 2 a brief description of the security problems inside a local network, the most well-known network security models are presented. This paper provides a review of the confidentiality in network security. Confidentiality is a property that aims to ensure that only authorized users can access the required information and data while unauthorized users and third parties cannot learn it. Confidentiality components encompass the use of access controls