# Modeling and Performance Analysis of Satellite Network Moving Target Defense System with Petri Nets
###### Abstract  
With the development of satellite communication networks and the increase of satellite services, security problems have gradually become some of the most concerning issues. Researchers have made great efforts, including conventional safety methods such as secure transmission, anti-jamming, secure access, and especially the new generation of active defense technology represented by MTD. However, few scholars have theoretically studied the influence of active defense technique on the performance of satellite networks. Formal modeling and performance analysis have not been given sufficient attention. In this paper, we focus on the performance evaluation of satellite network moving target defense system. Firstly, two Stochastic Petri Nets (SPN) models are constructed to analyze the performance of satellite network in traditional and active defense states, respectively. Secondly, the steady-state probability of each marking in SPN models is obtained by using the isomorphism relation between SPN and Markov Chains (MC), and further key performance indicators such as average time delay, throughput, and the utilization of bandwidth are reasoned theoretically. Finally, the proposed two SPN models are simulated based on the PIPE platform. In addition, the effect of parameters on the selected performance indexes is analyzed by varying the values of different parameters. The simulation results prove the correctness of the theoretical reasoning and draw the key factors affecting the performance of satellite network, which can provide an important theoretical basis for the design and performance optimization of the satellite network moving target defense system. s 2021 13 1262 13 126  
and space technology [1]. Satellite network is a special kind of communication network, which has many unique advantages compared with traditional terrestrial networks [2]:  
1. Long distance communication. The cost of communication is independent of distance, so it is particularly suitable for correspondence over the long haul and in areas with few human activities;
2. Wide communication coverage. Each satellite can cover 42.4% of the global surface, and three GEO satellites can cover the global surface;
3. Wide communication band and large capacity;
4. Flexible. Satellite communications can be set up anywhere, regardless of geographical conditions, whether in large cities or remote mountainous areas;
5. Reliable communication link and strong resistance to natural disasters. All of these unique merits make satellites play an irreplaceable role when terrestrial communication networks are unavailable or seriously damaged. In recent years, satellite networks have developed rapidly and have become an important pillar in the construction of global information infrastructure. In some countries, satellite Internet has been included in the category of \"New Infrastructure\" [3]. In today's life, the increasing level of information technology has brought great convenience to society, but the threat of cyber attacks is also growing. Satellite networks are more vulnerable to the threat of break-ins and attacks due to the openness of its channels. Compared to traditional terrestrial network equipment, satellite equipment is expensive and extremely difficult to repair and recover. Once attacked, it will cause incalculable losses to the country and society [4; 5]. More and more scholars have started to pay attention to the security of satellite networks, and build satellite network security protection systems by adopting effective security mechanisms to avoid as much as possible the degradation of network performance or even complete paralysis caused by various attacks. Traditional cyber security techniques such as information encryption, identity authentication and access control can enhance the communication security of satellite networks to some extent, while they can no longer meet the increasingly diversified needs of space tasks.