Industrial Automatic Control Systems and Controllers Annotation << Back ICS Firewalls and their Operating Principle Yu.Yu. Gromov, P.I. Karasev, D.S. Korshunov, Yu.A. Parshenkova The active spread of information technologies leads to the continuous development of innovative solutions in the field of information security. To date, the development of tools that allow protecting information resources in both the household and professional spheres of human life is being update. Of particular importance is the first direction of development of information security solutions. The purpose of the current article is to analyze the issue of the relevance and eff ectiveness of using firewalls to protect computer networks. The peculiarity of the work also lies in a more detailed analysis of the principles of operation of these information security solutions. The scientifi c value of the work lies in the systematization of knowledge on the issues and features of the use of firewalls in computer networks of modern organizations. The presented materials can be useful in solving problems of ensuring information security at enterprises with one or more computer networks. Based on the results of the work, conclusions are form regarding the relevance and necessity of using firewalls in the professional sphere of human life. Keywords: firewall, information security, computer network, operating principle, information protection. DOI: 10.25791/asu.3.2023.1423 Pp. 24-29.