Ali Khodayaran - K. N. Toosi University of Technology Student of Computer Networks at Khwaja Nasiruddin Toosi University Tehran, Iran

Network security becomes an important and vital issue in the topic of networking because all personal information and business organizations are shared in computer networks. We all know very well that there is no definitive and accurate method to protect the networks of organizations and companies from people's intrusion. Although the methods of intrusion and damage to the network are improving, the technologies to prevent intrusion and maintain the security of the network have also improved over time. Network security is one of the important concerns of organizations and businesses. Therefore, in this article, we intend to investigate network security and know what network security is. Also, let's review the history of network security and know what are the principles of this security system. In the following note, what are the network security methods and how to ensure the physical security of the network. In the end, he checked the specialized knowledge of network security

Network Security, Network attacks, Firewall, Security Vulnerabilities, Attack-defense