Anatomy of the Third-Party Web Tracking Ecosystem

The presence of third-party tracking on websites has become customary. However, our understanding of the third-party ecosystem is still very rudimentary. We examine third-party trackers from a geographical perspective, observing the third-party tracking ecosystem from 29 countries across the globe. When examining the data by region (North America, South America, Europe, East Asia, Middle East, and Oceania), we observe significant geographical variation between regions and countries within regions. We find trackers that focus on specific regions and countries, and some that are hosted in countries outside their expected target tracking domain. Given the differences in regulatory regimes between jurisdictions, we believe this analysis sheds light on the geographical properties of this ecosystem and on the problems that these may pose to our ability to track and manage the different data silos that now store personal data about us all

Revisiting Content Availability in Distributed Online Social Networks

Online Social Networks (OSN) are among the most popular applications in today's Internet. Decentralized online social networks (DOSNs), a special class of OSNs, promise better privacy and autonomy than traditional centralized OSNs. However, ensuring availability of content when the content owner is not online remains a major challenge. In this paper, we rely on the structure of the social graphs underlying DOSN for replication. In particular, we propose that friends, who are anyhow interested in the content, are used to replicate the users content. We study the availability of such natural replication schemes via both theoretical analysis as well as simulations based on data from OSN users. We find that the availability of the content increases drastically when compared to the online time of the user, e. g., by a factor of more than 2 for 90% of the users. Thus, with these simple schemes we provide a baseline for any more complicated content replication scheme.Comment: 11pages, 12 figures; Technical report at TU Berlin, Department of Electrical Engineering and Computer Science (ISSN 1436-9915

Are People Really Social on Porn 2.0?

Social Web 2.0 features have become a vital component in a variety of multimedia systems, e.g., Last.fm, Flickr and Spotify. Interestingly, adult video websites are also starting to adopt these Web 2.0 principles, giving rise to the term ``Porn 2.0''. This paper examines a large Porn 2.0 social network, through data covering 563k users. We explore a number of unusual behavioural aspects that set this apart from more traditional multimedia social networks, including differences in browsing activity, social communications and relationship creation. We also analyse the nature and behaviour of content sharing, highlighting the role it plays in the Porn 2.0 community, as well as the preferences that users have when deciding what to consume. We particularly explore the impact that gender and sexuality have on these issues, showing their vital importance for aspects such as profile popularity

How happy are your flows: an empirical study of packet losses in router buffers

Studies of Internet traffic have revealed that traffic is consistent with self-similar scaling, shows long-range dependence, and that flow sizes are consistent with heavytailed distributions. However, how such characteristics affect fundamental network properties such as buffer overflows and therefore the loss process and link utilization has not been explored in detail. Relying on advanced instrumentation via NetFPGA cards, we perform a sensitivity study of the packet loss process within routers for different network load levels, flow size distributions, and buffer sizes. We find that packet losses do not affect all flows similarly. Depending on the network load and the buffer sizes, some flows either suffer from significantly more drops or significantly less drops than the average loss rate. Very few flows actually observe a loss rate similar to the average loss rate. Therefore, any single flow is very unlikely to observe the global packet loss process. Furthermore, the loss process can exhibit scaling properties

Assessing the geographic resolution of exhaustive tabulation for geolocating Internet hosts

peer reviewedGeolocation of Internet hosts relies mainly on exhaustive tabulation techniques. Those techniques consist in building a database, that keeps the mapping between IP blocks and a geographic location. Relying on a single location for a whole IP block requires using a coarse enough geographic resolution. As this geographic resolution is not made explicit in databases, we try in this paper to better understand it by comparing the location estimates of databases with a well-established active measurements-based geolocation technique. We show that the geographic resolution of geolocation databases is far coarser than the resolution provided by active measurements for individual IP addresses. Given the lack of information in databases about the expected location error within each IP block, one cannot havemuch confidence in the accuracy of their location estimates. Geolocation databases should either provide information about the expected accuracy of the location estimates within each block, or reveal information about how their location estimates have been built, unless databases have to be trusted blindly.FP6-FET ANA (FP6-IST- 27489

Measurements and analysis of a major adult video portal

Today the Internet is a large multimedia delivery infrastructure, with websites such as YouTube appearing at the top of most measurement studies. However, most traffic studies have ignored an important domain: adult multimedia distribution. Whereas, traditionally, such services were provided primarily via bespoke websites, recently these have converged towards what is known as "Porn 2.0". These services allow users to upload, view, rate and comment on videos for free (much like YouTube). Despite their scale, we still lack even a basic understanding of their operation This paper addresses this gap by performing a large-scale study of one of the most popular Porn 2.0 websites: YouPorn. Our measurements reveal a global delivery infrastructure that we have repeatedly crawled to collect statistics (on 183k videos). We use this data to characterise the corpus, as well as to inspect popularity trends and and how they relate to other features, e.g., categories and ratings. To explore our discoveries further, we use a small-scale user study, highlighting key system implications

Exploiting Locality of Churn for FIB Aggregation

Snapshots of the Forwarding Information Base (FIB) in Internet routers can be compressed (or aggregated) to at least half of their original size, as shown by previous studies. In practice however, the permanent stream of updates to the FIB due to routing updates complicates FIB aggregation: keeping an optimally aggregated FIB in face of these routing updates is algorithmically challenging. A sensible trade-off has to be found between the aggregation gain and the number of changes to the aggregated FIB. This paper is the first to investigate whether the spatial and temporal locality properties of updates to the tree-like FIB data structure can be leveraged by online FIB aggregation. Our contributions include (a) an empirical study of the locality of updates in public Internet routing data, (b) the specification and simulations of our Locality-aware FIB Aggregation algorithm (LFA), and (c) a competitive analysis that sheds light on the performance of online algorithms under worst-case update streams. Our results show that even a simple algorithm like LFA can effectively exploit the locality of FIB churn to keep low the number of updates to the aggregated FIB, as most FIB updates affect only a small number of regions in the FIB