Measuring the bittorrent ecosystem: techniques, tips, and tricks

BitTorrent is the most successful peer-to-peer application. In the last years the research community has studied the BitTorrent ecosystem by collecting data from real BitTorrent swarms using different measurement techniques. In this article we present the first survey of these techniques that constitutes a first step in the design of future measurement techniques and tools for analyzing large-scale systems. The techniques are classified into macroscopic, microscopic, and complementary. Macroscopic techniques allow us to collect aggregated information of torrents and present very high scalability, able to monitor up to hundreds of thousands of torrents in short periods of time. Microscopic techniques operate at the peer level and focus on understanding performance aspects such as the peers¿ download rates. They offer higher granularity but do not scale as well as macroscopic techniques. Finally, complementary techniques utilize recent extensions to the BitTorrent protocol in order to obtain both aggregated and peer-level information. The article also summarizes the main challenges faced by the research community to accurately measure the BitTorrent ecosystem such as accurately identifying peers and estimating peers' upload rates. Furthermore, we provide possible solutions to address the described challenges.The research leading to these results has received funding from the European Union Seventh Framework Program (FP7/2007-2013) through the TREND NoE project (grant agreement no. 25774) and the Regional Government of Madrid through the MEDIANET project (S- 2009/TIC-1468).Publicad

IPv4 address sharing mechanism classification and tradeoff analysis

The growth of the Internet has made IPv4 addresses a scarce resource. Due to slow IPv6 deployment, IANA-level IPv4 address exhaustion was reached before the world could transition to an IPv6-only Internet. The continuing need for IPv4 reachability will only be supported by IPv4 address sharing. This paper reviews ISP-level address sharing mechanisms, which allow Internet service providers to connect multiple customers who share a single IPv4 address. Some mechanisms come with severe and unpredicted consequences, and all of them come with tradeoffs. We propose a novel classification, which we apply to existing mechanisms such as NAT444 and DS-Lite and proposals such as 4rd, MAP, etc. Our tradeoff analysis reveals insights into many problems including: abuse attribution, performance degradation, address and port usage efficiency, direct intercustomer communication, and availability

Considerations around transport header confidentiality, network operations, and the evolution of Internet transport protocols

To protect user data and privacy, Internet transport protocols have supported payload encryption and authentication for some time. Such encryption and authentication are now also starting to be applied to the transport protocol headers. This helps avoid transport protocol ossification by middleboxes, mitigate attacks against the transport protocol, and protect metadata about the communication. Current operational practice in some networks inspect transport header information within the network, but this is no longer possible when those transport headers are encrypted. This document discusses the possible impact when network traffic uses a protocol with an encrypted transport header. It suggests issues to consider when designing new transport protocols or features