# Random Routing Algorithm for Enhancing the Cybersecurity of LEO Satellite Networks
## 1 Introduction  
The interest in LEO satellite networks (LSNs) is increasing with the recent launches from SpaceX, Oneweb, Telesat, and Globastar [1]. The modern LSN consists of hundreds of satellites in orbit, causing it to be a dense network that will provide seamless communication services to public and government agencies. These dense LSNs aim to provide optical fiber-like Internet services with lower latency [2, 3]. Satellites provide a myriad of services including communication, broadcasting, GPS and navigation, banking. Internet of Things (IoT), early warning systems, meteorology, remote sensing, and surveillance [4, 5]. With the increasing role of LSNs in the communication infrastructure, several security issues have begun to appear at the forefront that have been largely neglected so far [6, 7]. One of such issues is the increasing cyberattacks on satellite networks, which will be detrimental to the communication infrastructure and cause a lot of damage to service providers, the end users, and governments. Distributed Denial of Service (DDoS) attacks, which have been a huge threat to the Internet since its early days, have been used effectively for a while against satellite networks. In [8], the authors show that a DDoS attack is feasible in the LSN and that the traditional mitigation and prevention methods are ineffective because of the special characteristics of these networks. The research on such attacks is an ever-going battlefield between attackers constantly modifying their tools and defenders modifying their approaches to oversee new attacks. In 2015, 20% of businesses with 50 or more employees suffered atleast one DDoS attack and 26% of DDoS attacks led to data loss [9]. Especially in the satellite communication sector, the DDoS attack frequency increased by 255% from the second half of 2018 to first half of 2019 and increased yet again by 295% from the first half of 2019 to its second half [10]. The typical results of such an attack include network infrastructure, service continuity, and business reputation damages. Furthermore, these can have devastating costs, e.g., the average cost of downtime for an enterprise can reach up to USD 2 million [11]. There are three kinds of satellite networks: Geosynchronous equatorial orbit (GEO), Medium earth orbit (MEO), and LEO satellite. The GEO satellites are located at an altitude of 36,000 km from the earth and remain fixed in the sky when observed from the ground. Due to larger distances, they have higher propagation losses and transmission delays besides not able to cover high latitude areas [12]. The non-geostationary satellites have recently gathered more attention due to seamless connectivity, lower propagation delays, lower expense, and broadband communication [13; 14]. The NGSO satellites include the MEO at altitudes between 8000 and 20,000 km and LEO between 400 and 2000 km above earth. Recently, several mega-constellations of LEO satellites have been launched by Starlink, Telesat, Globastar, Oneweb, and Iridium that will provide connectivity and broadband communication services [15]. The LSN offers lower transmission delay and propagation losses causing it to be attractive for ultra-reliable low-latency communication. However, there are significant challenges in the routing algorithms of LSNs. The routing in terrestrial networks relies on the routing tables obtained from the network topology that leads to greater network overhead and slow convergence [16]. Besides, the demands of computational power and storage can be met for these routers. However, in the case of LSNs, the network topology is dynamically varying and has limited onboard computation and storage. The high mobility of LEO satellites causes instability in the established paths [17]. In [18], the authors describe how a new architecture called NDN (Named Data Architecture), which is already being considered instead of traditional TCP/IP architecture, may solve that problem of mobility in the inter-satellite links.