This article proposes a network traffic monitoring system with filtering elements at the data link layer (L2) of the OSI model. This article presents the general requirements and approaches to the construction of the proposed monitoring and filtering system. The developed device is built on the basis of SDN technology, which makes it possible to create a more flexible and multifunctional network device compared to traditional network devices. In the process of developing the device, standard methods and components available to the masses were used. Under the conditions of the tasks set, a schematic diagram of the developed device based on the TE0714 TRM model board and the SFP standard transceiver is presented. It is proposed to use the device for a monitoring system with filtering elements. Network traffic monitoring is proposed to be implemented based on the SNMP protocol to collect information from critical network nodes. It is proposed to implement network traffic filtering based on a "white" list of MAC addresses to limit the list of devices that have access to the system. The practical significance of this article lies in the description of the approach to the development of a fundamental device for monitoring public and personal networks with flexibly defined additional and basic functions. The proposed device, thanks to the use of SDN technology, provides individual customization for customer requests, which means the possibility of expanding functionality without purchasing new hardware and firmware. The proposed device, due to the use of SDN technology, provides individual customization for customer requests, which means the possibility of expanding the functionality without purchasing new hardware and firmware.

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