Estimating IPv4 address space usage with capture-recapture

As of April 2013 almost 95% of the IPv4 address space has been allocated. Yet, the transition to IPv6 is still relatively slow. One reason could be existing “IPv4 reserves” – allocated but unused IPv4 addresses. Knowing how many addresses are actively used is important to predict a potential IPv4 address market, predict the IPv6 deployment time frame, and measure progressive exhaustion after the IPv4 space is fully allocated. Unfortunately, only a fraction of hosts respond to active probes, such as “ping”. We propose a capture-recapture method to estimate the actively used IPv4 addresses from multiple incomplete data sources, including “ping” censuses, network traces and server logs. We estimate that at least 950–1090 million IPv4 addresses are used, which is 36–41% of the publicly routed space. We analyse how the utilisation depends on various factors, such as region, country and allocation prefix length

Mitigating sampling error when measuring internet client IPv6 capabilities

Despite the predicted exhaustion of unallocated IPv4 addresses be- tween 2012 and 2014, it remains unclear how many current clients can use its successor, IPv6, to access the Internet. We propose a refinement of previous measurement studies that mitigates intrin- sic measurement biases, and demonstrate a novel web-based tech- nique using Google ads to perform IPv6 capability testing on a wider range of clients. After applying our sampling error reduction, we find that 6% of world-wide connections are from IPv6-capable clients, but only 1–2% of connections preferred IPv6 in dual-stack (dual-stack failure rates less than 1%). Except for an uptick around IPv6-day 2011 these proportions were relatively constant, while the percentage of connections with IPv6-capable DNS resolvers has in- creased to nearly 60%. The percentage of connections from clients with native IPv6 using happy eyeballs has risen to over 20

Collaborative and privacy-preserving estimation of IP address space utilisation

Exhaustion of the IPv4 address space is driving mitigation technologies, such as carrier-grade NAT or IPv6. Understanding this driver requires knowing how much allocated IPv4 space is actively used over time – a non-trivial goal due to privacy concerns and practical measurement challenges. To address this gap we present a collaborative and privacy-preserving capture-recapture (CR) technique for estimating IP address space utilisation. Public and private datasets of IP addresses observed by multiple independent collaborators can be combined for CR analysis, without any individual collaborator's privately observed addresses leaking to the others. We show that CR estimation is much more accurate than assuming all used addresses are observed, and that our scheme scales well to datasets of over a billion addresses across several collaborators. We estimate that 1.2 billion IPv4 addresses and 6.5 million /24 subnets were actively used at the end of 2014, and also analyse address usage depending on RIR and country

Investigating the IPv6 teredo tunnelling capability and performance of internet clients

The Teredo auto-tunnelling protocol allows IPv6 hosts behind IPv4 NATs to communicate with other IPv6 hosts. It is enabled by default on Windows Vista and Windows 7. But Windows clients are self-constrained: if their only IPv6 access is Teredo, they are unable to resolve host names to IPv6 addresses. We use web-based measurements to investigate the (latent) Teredo capability of Internet clients, and the delay introduced by Teredo. We compare this with native IPv6 and 6to4 tunnelling capability and delay. We find that only 6--7% of connections are from fully IPv6-capable clients, but an additional 15--16% of connections are from clients that would be IPv6-capable if Windows Teredo was not constrained. However, Teredo increases the median latency to fetch objects by 1--1.5 seconds compared to IPv4 or native IPv6, even with an optimally located Teredo relay. Furthermore, in many cases Teredo fails to establish a tunnel