Measurement and Analysis of IPv6 Interface Identifier Patterns in the Real World

Interface Identifiers (IIDs) are critical components of IPv6 addresses, significantly impacting user privacy and the feasibility of network reconnaissance. RFC 7707 previously provided a comprehensive analysis of IID patterns based on data from the early stages of IPv6 deployment. However, with the widespread adoption of privacy-enhancing standards such as RFC 7217, historical data no longer accurately reflects the current IPv6 ecosystem. This document provides updated measurements of IID patterns by utilizing an improved pattern recognition method and incorporating novel data sources, such as public mailing lists. The measurement data reveals that while "Low-byte" patterns have decreased significantly in server addresses, a substantial number of seemingly random addresses actually belong to non-random, specific patterns, implying that heuristic scanning remains a viable vector. Furthermore, while client devices have widely adopted randomized addresses-effectively enhancing privacy-Client Premise Equipment (CPE) routers continue to exhibit a high usage rate of IEEE EUI-64 addresses, constituting an often-overlooked privacy risk. This document aims to update the statistics and analysis regarding IID pattern distribution found in RFC 7707, providing essential insights for modern network defense strategies and standard compliance.