Peer-to-peer networks have been quite thoroughly measured over the past years; however it is interesting to note that the BitTorrent Mainline DHT has received very little attention even though it is by far the largest of currently active overlay systems, as our results show. As Mainline DHT differs from other systems, existing measurement methodologies are not appropriate for studying it. In this talk we present an efficient methodology for estimating the number of active users in the network. We have identified an omission in previous methodologies used to measure the size of the network and our methodology corrects this. This omission may lead to inaccuracies of up to 40% in the number of active users. Our method is based on modeling crawling inaccuracies as a Bernoulli process. It guarantees a very accurate estimation and is able to provide the estimate in about 5 seconds. Through experiments in controlled situations, we demonstrate the accuracy of our method and show the causes of the inaccuracies in previous work, by reproducing the incorrect results. Besides accurate network size estimates, our methodology can be used to detect network anomalies, in particular Sybil attacks in the network. We also report on the results from our measurements which have been going on for almost 2.5 years and are the first long-term study of Mainline DHT.

Publish/subscribe (pub/sub) is a popular communication paradigm in the design of large-scale distributed systems. We are witnessing an increasingly widespread use of the pub/sub for wide array of applications both in industry and academia and yet there is a lack of detailed study of a large-scale real-world pub/sub system.

Virtualization is a powerful paradigm in computer science, as it allows to decouple software and services from the constraints of the underlying physical infrastructure. Virtualization is also one of the main innovation motors in today's Internet

Visible light is ubiquitous in the cyber-space nowadays. In this talk, I will introduce our recent work about how to harness visible light for mobile computing applications in both temporal and spatial design domains. Our work leverages the fact that the fluorescent light intensity changes with a stable period, which can serve as both a global time reference and an indoor environment indicator.

Several members and stakeholders of IMDEA Networks Institute are leading the organization of ACM e-Energy 2014. Marco Ajmone Marsan and Antonio Fernández Anta are both long-standing researchers at the Institute. Two leading international figures in networking research, Jim Kurose from University of Massachusetts at Amherst (USA) and Jon Crowcroft, from University of Cambridge (UK), are both members of IMDEA Networks’ Scientific Council. Ajmone, Fernández Anta, and Kurose are Steering Committee members the ACM e-Energy conference, whereas Crowcroft is the General co-chair of the 2014 edition.

Our objective is to guarantee that vehicles that coordinate their operations will operate safely with all of the other vehicles, implemented by all of the other manufacturers, on the roadway.

With the increasing availability of configurable network equipments, the research has moved from proposals to improve quality of service in the wireless standards, to complete potential chaos when it becomes accessible to every user. In this talk we go through this evolution and discuss its impact on the network and on the user.

Bitcoin is a decentralized peer-to-peer payments network. It is the first and most widely used example of a new kind of money known as cryptocurrency. Transactions are fast, non-repudiable and almost anonymous. Fees are extremely cheap and every single transaction is stored in a ledger called the block chain.

Information and communication technologies (ICTs) often fail to perform well in environments and scenarios that were not envisioned at the time of the ICTs creation. Examples of such failures include poor usability of traditional WiFi networks in resource-constrained rural areas, geographically-dependent performance of centralised networked systems, and context-insensitive behaviour of ubiquitous computing devices.