On the Estimation of the Number of Unreachable Peers in the Bitcoin P2P Network by Observation of Peer Announcements

摘要: Bitcoin is based on a P2P network that used to propagate transactions and blocks. While the design intends hide topology of network, information about required understand from scientific point view. Thus, there natural tension between 'desire' for unobservability one hand, observability other hand. On middle ground, would at least be interested some statistical features like number peers participate in propagation This composed reachable accept incoming connections unreachable do not connections. can measured, it inherently difficult determine peers. only estimated indicators. In this paper, we first define our understanding then propose PAL (Passive Announcement Listening) method which gives an estimate by observing ADDR messages announce active IP addresses network. The allows detecting indicate they provide services useful conjunction with previous methods, help get better We use analyze data long-term measurement insights into development over more than five years 2015 2020. Results show 31,000 providing were per day end year An empirical validation indicates approach finds 50 % services.