Bringing New Life to Old Tools: Measuring Source Address Validation Deployment with 6in4 Tunnels

Source Address Validation (SAV) is a security mechanism deployed at network boundaries to prevent packets with illegal source addresses from crossing these boundaries. While SAV plays an important role in mitigating source address spoofing, its deployment across the global Internet remains limited. Measuring SAV deployment is essential for enhancing the understanding of the security landscape of networks. In this study, we propose a novel method for measuring SAV deployment based on 6 in 4 tunnels, complementing existing measurement work. Using this method, we measure inbound SAV for IPv4 and outbound SAV for IPv6, obtaining results from 12,417 and 2,104 Autonomous Systems (ASes), respectively. Based on our measurements, we analyze factors that may influence SAV deployment, including network address space size, AS type, and geographical location. Additionally, we provide a global heatmap of spoofable rates for networks in different countries and regions. Note that the measuring method using bin4 tunnels we introduce is not only applicable to SAV measurements but also holds potential for other measurement tasks, such as connectivity testing and transmission path discovery. This method offers a new way for large-scale measurement tasks across different networks, which may benefit future research.