Satellite Internet (SI) is a new way to provide internet access all over the world. It will bring great convenience to international communication. Compared with the traditional communication networks, SI has a significant change in network architecture and communication model, which will have an important impact on national information network security. For example, the global interconnected SI consists of a large number of small satellites and each satellite has multi-beams to cover a vast area, which leads to the disorderly flow of information across the border, and greatly increases the difficulty of network protection. Therefore, it is necessary to closely track the development of SI and analyze security problems brought by SI. In this paper, we analyze the security risks of SI from the perspective of national security, network security and equipment security, and thirteen security issues have been summarized to provide reference for the healthy development of SI industry.

While Role-Based Access Control Model (RBAC) is being analyzed, the concept of Role of Timedomain Based Access Control Model (T-RBAC) is put forward. With time-domain added, both timedomain and authority control roles. The basic idea of T-RBAC is introduced and described formally, and the safely of this model is analyzed. The research shows that T-RBAC fulfills both rules of information security, which are principle of least privilege and separation of duties. With practical application of T-RBCA, it can handle most of the time-related or authority-related problems. What's more, it also increases the security level, flexibility and dynamic adaptation of the system and has lower complexity than system only handled by authority. This model also can solve conflicts caused by authority.