Internet background radiation revisited

The monitoring of packets destined for routeable, yet unused, Internet addresses has proved to be a useful technique for measuring a variety of specific Internet phenomenon (e.g., worms, DDoS). In 2004, Pang et al. stepped beyond these targeted uses and provided one of the first generic characterizations of this non-productive traffic, demonstrating both its significant size and diversity. However, the six years that followed this study have seen tremendous changes in both the types of malicious activity on the Internet and the quantity and quality of unused address space. In this paper, we revisit the state of Internet "background radiation" through the lens of two unique data-sets: a five-year collection from a single unused 8 network block, and week-long collections from three recently allocated 8 network blocks. Through the longitudinal study of the long-lived block, comparisons between blocks, and extensive case studies of traffic in these blocks, we characterize the current state of background radiation specifically highlighting those features that remain invariant from previous measurements and those which exhibit significant differences. Of particular interest in this work is the exploration of address space pollution, in which significant non uniform behavior is observed. However, unlike previous observations of differences between unused blocks, we show that increasingly these differences are the result of environmental factors (e.g., misconfiguration, location), rather than algorithmic factors. Where feasible, we offer suggestions for clean up of these polluted blocks and identify those blocks whose allocations should be withheld.