Beyond Counting: New Perspectives on the Active IPv4 Address Space

In this study, we report on techniques and analyses that enable us to capture Internet-wide activity at individual IP address-level granularity by relying on server logs of a large commercial content delivery network (CDN) that serves close to 3 trillion HTTP requests on a daily basis. Across the whole of 2015, these logs recorded client activity involving 1.2 billion unique IPv4 addresses, the highest ever measured, in agreement with recent estimates. Monthly client IPv4 address counts showed constant growth for years prior, but since 2014, the IPv4 count has stagnated while IPv6 counts have grown. Thus, it seems we have entered an era marked by increased complexity, one in which the sole enumeration of active IPv4 addresses is of little use to characterize recent growth of the Internet as a whole. With this observation in mind, we consider new points of view in the study of global IPv4 address activity. Our analysis shows significant churn in active IPv4 addresses: the set of active IPv4 addresses varies by as much as 25% over the course of a year. Second, by looking across the active addresses in a prefix, we are able to identify and attribute activity patterns to network restructurings, user behaviors, and, in particular, various address assignment practices. Third, by combining spatio-temporal measures of address utilization with measures of traffic volume, and sampling-based estimates of relative host counts, we present novel perspectives on worldwide IPv4 address activity, including empirical observation of under-utilization in some areas, and complete utilization, or exhaustion, in others.Comment: in Proceedings of ACM IMC 201

A Multi-perspective Analysis of Carrier-Grade NAT Deployment

As ISPs face IPv4 address scarcity they increasingly turn to network address translation (NAT) to accommodate the address needs of their customers. Recently, ISPs have moved beyond employing NATs only directly at individual customers and instead begun deploying Carrier-Grade NATs (CGNs) to apply address translation to many independent and disparate endpoints spanning physical locations, a phenomenon that so far has received little in the way of empirical assessment. In this work we present a broad and systematic study of the deployment and behavior of these middleboxes. We develop a methodology to detect the existence of hosts behind CGNs by extracting non-routable IP addresses from peer lists we obtain by crawling the BitTorrent DHT. We complement this approach with improvements to our Netalyzr troubleshooting service, enabling us to determine a range of indicators of CGN presence as well as detailed insights into key properties of CGNs. Combining the two data sources we illustrate the scope of CGN deployment on today's Internet, and report on characteristics of commonly deployed CGNs and their effect on end users

Temporal and Spatial Classification of Active IPv6 Addresses

There is striking volume of World-Wide Web activity on IPv6 today. In early 2015, one large Content Distribution Network handles 50 billion IPv6 requests per day from hundreds of millions of IPv6 client addresses; billions of unique client addresses are observed per month. Address counts, however, obscure the number of hosts with IPv6 connectivity to the global Internet. There are numerous address assignment and subnetting options in use; privacy addresses and dynamic subnet pools significantly inflate the number of active IPv6 addresses. As the IPv6 address space is vast, it is infeasible to comprehensively probe every possible unicast IPv6 address. Thus, to survey the characteristics of IPv6 addressing, we perform a year-long passive measurement study, analyzing the IPv6 addresses gleaned from activity logs for all clients accessing a global CDN. The goal of our work is to develop flexible classification and measurement methods for IPv6, motivated by the fact that its addresses are not merely more numerous; they are different in kind. We introduce the notion of classifying addresses and prefixes in two ways: (1) temporally, according to their instances of activity to discern which addresses can be considered stable; (2) spatially, according to the density or sparsity of aggregates in which active addresses reside. We present measurement and classification results numerically and visually that: provide details on IPv6 address use and structure in global operation across the past year; establish the efficacy of our classification methods; and demonstrate that such classification can clarify dimensions of the Internet that otherwise appear quite blurred by current IPv6 addressing practices

An Internet Heartbeat

Obtaining sound inferences over remote networks via active or passive measurements is difficult. Active measurement campaigns face challenges of load, coverage, and visibility. Passive measurements require a privileged vantage point. Even networks under our own control too often remain poorly understood and hard to diagnose. As a step toward the democratization of Internet measurement, we consider the inferential power possible were the network to include a constant and predictable stream of dedicated lightweight measurement traffic. We posit an Internet "heartbeat," which nodes periodically send to random destinations, and show how aggregating heartbeats facilitates introspection into parts of the network that are today generally obtuse. We explore the design space of an Internet heartbeat, potential use cases, incentives, and paths to deployment

A Survey Of IPv6 Address Usage In The Public Domain Name System

The IPv6 protocol has been slowly increasing in use on the Internet. The main reason for the development of the protocol is that the address space provided by IPv4 is nearing exhaustion. The pool of addresses provided by IPv6 is 296 times larger than IPv4, and should be sufficient to provide an address for every device for the foreseeable future. Another potential advantage of this significantly large address space is the use of randomly assigned addresses as a security barrier as part of a defence in depth strategy. This research examined the addresses allocated by those implementing IPv6 to determine what method or pattern of allocation was being used by adopters of the protocol. This examination was done through the use of DNS queries of the AAAA IPv6 host record using public DNS servers. It was observed that 55.84% of IPv6 addresses were in the range of 0 to (232 − 1). For those addresses with unique interface identifier (IID) portions, a nearly equal number of sequential and random IIDs were observed. Hong Kong and Germany were found to have the greatest number of IPv6 addresses. These results suggest that adopters are allocating most addresses sequentially, meaning that no security advantage is being obtained. It is unclear as to whether this is through design or the following of accepted practice. Future research will continue to survey the IPv6 address space to determine whether the patterns observed here remain constant

Analysing the IoT Ecosystem: the Barriers to Commercial Traction

The Internet of Things (IoT) has come to mean all things to all people. Combined with the huge amount of interest and investment into this emerging opportunity, there is a real possibility that the arising confusion will hamper adoption by the mass market. This paper proposes a phased model of the IoT ecosystem development, starting with infrastructure establishment, and culminating in exploitation through the creation of new companies and business models. It does not attempt to quantify the emerging opportunities, relying instead on the many publications dedicated to detailed market analysis. The focus is to place the opportunities in context, demonstrate the importance of sensor system technology underpinning the emerging IoT revolution, and suggests areas where Europe can establish a leadership position. Throughout the paper, examples of the likely protagonists have been used by way of illustration

Service quality measurements for IPv6 inter-networks

Measurement-based performance evaluation of network traffic is becoming very important, especially for networks trying to provide differentiated levels of service quality to the different application flows. The non-identical response of flows to the different types of network-imposed performance degradation raises the need for ubiquitous measurement mechanisms, able to measure numerous performance properties, and being equally applicable to different applications and transports. This paper presents a new measurement mechanism, facilitated by the steady introduction of IPv6 in network nodes and hosts, which exploits native features of the protocol to provide support for performance measurements at the network (IP) layer. IPv6 Extension Headers have been used to carry the triggers involving the measurement activity and the measurement data in-line with the payload data itself, providing a high level of probability that the behaviour of the real user traffic flows is observed. End-to-end one-way delay, jitter, loss, and throughput have been measured for applications operating on top of both reliable and unreliable transports, over different-capacity IPv6 network configurations. We conclude that this technique could form the basis for future Internet measurements that can be dynamically deployed where and when required in a multi-service IP environment

An investigation into Off-Link IPv6 host enumeration search methods

This research investigated search methods for enumerating networked devices on off-link 64 bit Internet Protocol version 6 (IPv6) subnetworks. IPv6 host enumeration is an emerging research area involving strategies to enable detection of networked devices on IPv6 networks. Host enumeration is an integral component in vulnerability assessments (VAs), and can be used to strengthen the security profile of a system. Recently, host enumeration has been applied to Internet-wide VAs in an effort to detect devices that are vulnerable to specific threats. These host enumeration exercises rely on the fact that the existing Internet Protocol version 4 (IPv4) can be exhaustively enumerated in less than an hour. The same is not true for IPv6, which would take over 584,940 years to enumerate a single network. As such, research is required to determine appropriate host enumeration search methods for IPv6, given that the protocol is seeing increase global usage. For this study, a survey of Internet resources was conducted to gather information about the nature of IPv6 usage in real-world scenarios. The collected survey data revealed patterns in the usage of IPv6 that influenced search techniques. The research tested the efficacy of various searching algorithms against IPv6 datasets through the use of simulation. Multiple algorithms were devised to test different approaches to host enumeration against 64 bit IPv6 subnetworks. Of these, a novel adaptive heuristic search algorithm, a genetic algorithm and a stripe search algorithm were chosen to conduct off-link IPv6 host enumeration. The suitability of a linear algorithm, a Monte Carlo algorithm and a pattern heuristics algorithm were also tested for their suitability in searching off-link IPv6 networks. These algorithms were applied to two test IPv6 address datasets, one comprised of unique IPv6 data observed during the survey phase, and one comprised of unique IPv6 data generated using pseudorandom number generators. Searching against the two unique datasets was performed in order to determine appropriate strategies for off-link host enumeration under circumstances where networked devices were configured with addresses that represented real-word IPv6 addresses, and where device addresses were configured through some randomisation function. Whilst the outcomes of this research support that an exhaustive enumeration of an IPv6 network is infeasible, it has been demonstrated that devices on IPv6 networks can be enumerated. In particular, it was identified that the linear search technique and the variants tested in this study (pattern search and stripe search), remained the most consistent means of enumerating an IPv6 network. Machine learning methods were also successfully applied to the problem. It was determined that the novel adaptive heuristic search algorithm was an appropriate candidate for search operations. The adaptive heuristic search algorithm successfully enumerated over 24% of the available devices on the dataset that was crafted from surveyed IPv6 address data. Moreover, it was confirmed that stochastic address generation can reduce the effectiveness of enumeration strategies, as all of the algorithms failed to enumerate more than 1% of hosts against a pseudorandomly generated dataset. This research highlights a requirement for effective IPv6 host enumeration algorithms, and presents and validates appropriate methods. The methods presented in this thesis can help to influence the tools and utilities that are used to conduct host enumeration exercises