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Since the exhaustion of unallocated IP addresses at the Internet Assigned Numbers Authority (IANA), a market for IPv4 addresses has emerged. In complement to purchasing address space, leasing IP addresses is becoming increasingly popular. Leasing provides a cost-effective alternative for organizations that seek to scale up without a high upfront investment. However, malicious actors also benefit from leasing as it enables them to rapidly cycle through different addresses, circumventing security measures such as IP blocklisting. We explore the emerging IP leasing market and its implications for Internet security. We examine leasing market data, leveraging blocklists as an indirect measure of involvement in various forms of network abuse. In February 2025, leased prefixes were 2.89× more likely to be flagged by blocklists compared to non-leased prefixes. This result raises questions about whether the IP leasing market should be subject to closer scrutiny. 

We introduce new tools and vantage points to develop and integrate proactive techniques to attract IPv6 scan traffic, thus enabling its analysis. By deploying the largest-ever IPv6 proactive telescope in a production ISP network, we collected over 600M packets of unsolicited traffic from 1.9k Autonomous Systems in 10 months. We characterized the sources of unsolicited traffic, evaluated the effectiveness of five major features across the network stack, and inferred scanners' sources of target addresses and their strategies. 

Abstract Although Internet routing security best practices have recently seen auspicious increases in uptake, Internet Service Providers (ISPs) have limited incentives to deploy them. They are operationally complex and expensive to implement and provide little competitive advantage. The practices with significant uptake protect only against origin hijacks, leaving unresolved the more general threat of path hijacks. We propose a new approach to improved routing security that achieves four design goals: improved incentive alignment to implement best practices; protection against path hijacks; expanded scope of such protection to customers of those engaged in the practices; and reliance on existing capabilities rather than needing complex new software in every participating router. Our proposal leverages an existing coherent core of interconnected ISPs to create a zone of trust, a topological region that protects not only all networks in the region, but all directly attached customers of those networks. Customers benefit from choosing ISPs committed to the practices, and ISPs thus benefit from committing to the practices. We discuss the concept of a zone of trust as a new, more pragmatic approach to security that improves security in a region of the Internet, as opposed to striving for global deployment. We argue that the aspiration for global deployment is unrealistic, since the global Internet includes malicious actors. We compare our approach to other schemes and discuss how a related proposal, ASPA, could be used to increase the scope of protection our scheme achieves. We hope this proposal inspires discussion of how the industry can make practical, measurable progress against the threat of route hijacks in the short term by leveraging institutionalized cooperation rooted in transparency and accountability.