A Detailed Measurement View on IPv6 Scanners and Their Adaption to BGP Signals

Scanners are daily visitors of public IPv4 hosts. Scanning IPv6 nodes successfully is still a challenge, which an increasing crowd of actors tries to master. In this paper, we analyze IPv6 scanning under various network conditions to disclose the impact on scanning. We deploy four IPv6 network telescopes, including a reactive /48 telescope and a proactive /32 telescope that is periodically reconfigured by changing BGP announcements. We provide a longitudinal study of eleven months and classify the observed scanners w.r.t. their temporal behavior, their target and network selection strategies, as well as their individual tools, fingerprints, and correlations across categories. We find that silent subnets of larger covering prefixes remain mainly invisible, whereas BGP prefix announcements quickly attract attention by scanners. Based on our findings, we derive operational guidance on how to deploy network telescopes to increase visibility for IPv6 scanners and understand corresponding biases.