Pruning as Scanning: Towards Internet-Wide IPv6 Network Periphery Discovery

IPv6 network peripheries serve as the last-hop routing devices connecting customers, making the rapid discovery of periphery addresses crucial for Internet security and network measurement. Traditional IPv6 scanning methods, based on target generation algorithms (TGAs), often fall short due to mismatches between the patterns identified by TGAs and those inherent in IPv6 periphery addresses. To address this, we introduce Pruning-as-Scanning (PaS), a novel IPv6 scanning approach designed for fast global IPv6 periphery address discovery. Unlike previous methods, PaS initiates scanning from the entire IPv6 address space without relying on seed datasets. It systematically probes IPv6 Internet prefixes from the shortest to the longest, similar to a hierarchical search, while discarding those irrelevant prefixes (and sub-prefixes), i.e., space pruning. This reduces the complexity of searching the entire IPv6 address space, allowing comprehensive measurement of IPv6 endpoint subnets where periphery devices are installed. We implemented an asynchronous scanner prototype based on this principle. Real-world tests demonstrated that PaS outperformed existing methods in both probing scale and the number of identified periphery addresses. Our approach achieved the first comprehensive, global-scale IPv6 network periphery discovery, uncovering over 712 million IPv6 periphery addresses using 33 billion probe packets, averaging 4 million addresses per hour at an uplink of 50 kpps, significantly expanding the IPv6 address corpus.