This paper seeks to recognize the importance of cyber-security in national security, especially in the Internet environment, in the reality of building a smart ecosystem globally. Digital transformation and 5G innovation are happening more rapidly after the Corona 19 incident. The dailyization of information and communication and the expanded use of cyberspace can be felt in our real life. Globalization of global villages, the realization of smart cities and e-government in Korea is happening realistically. The use of information and communication in the essential daily life of everyone, such as finance, medical care, and education, is taken for granted, and the problem of cyber space is not a problem of only a specific group, but a problem that is directly related to all citizens. In order to protect the nation's important facilities and systems from packet-type cyber terrorism and attacks, we will look at monitoring and regulation of Internet circuits in terms of national security. The purpose of this study is to grasp the technical characteristics of communication restriction measures (aka' packet interception') on Internet circuits and to suggest the direction of investigation on interception of packets through comparative law review. Review and revise the Constitutional Inconsistency Case of the Constitutional Court regarding whether the communication restriction measures (packet interception) through the Internet line prescribed by the Communication Secret Protection Act contradicts the principle of excess provision and proportion of Article 37 (2) of the Constitution. Through the provisions of the secret law, we will look into the problems and improvement measures of the current cyber security system, especially related to national security.