Remote Operating System Classification over IPv6

Differences in the implementation of common networking protocols make it possible to identify the operating system of a remote host by the characteristics of its TCP and IP packets, even in the absence of application-layer information. This technique, "OS fingerprinting," is relevant to network security because of its relationship to network inventory, vulnerability scanning, and tailoring of exploits. Various techniques of fingerprinting over IPv4 have been in use for over a decade; however IPv6 has had comparatively scant attention in both research and in practical tools. In this paper we describe an IPv6-based OS fingerprinting engine that is based on a linear classifier. It introduces innovative classification features and network probes that take advantage of the specifics of IPv6, while also making use of existing proven techniques. The engine is deployed in Nmap, a widely used network security scanner. This engine provides good performance at a fraction of the maintenance costs of classical signature-based systems. We describe our work in progress to enhance the deployed system: new network probes that help to further distinguish operating systems, and imputation of incomplete feature vectors.