I. Introduction
With the rapid development of Internet of Things (IoT), it has been extended to vehicles for structuring the Intelligent Transportation System (ITS), i.e., the intelligent Internet of Vehicles (IoV). The intelligent IoV can provide credible and efficient communication services for vehicles to support kinds of applications, e.g., the Global Positioning System (GPS) and the advanced driving assistance system [1]. It is one of the most crucial techniques for employing the ITS in order to realize smart cities. Recently, various networking techniques, such as the 5G-enable communication network, have been already involved in IoVs to provide the higher bandwidth for users. Subsequently, an increasing number of users’ private information is transmitted over IoVs. Furthermore, the IoV is an open network for each user, though the user may be a possible attacker. Due to the openness of the IoV, it is usually attacked by various malware (e.g., the worm and the Trojan horse). Meanwhile, the Distributed Denial of Service (DDoS) attack has been a main menace for vehicles, in which the flooding DDoS attack known as a brute-force attack exhausts the cache and computing resources of vehicles. Thereby, to protect the privacy and security of users, the intrusion detection techniques have obtained more and more attention in IoVs [2]–[7].