Published on: 2014-08-18T23:20:54+00:00
In August 2014, Ivan Pustogarov discussed how Bitcoin peers maintain a history of forwarded addresses to prevent retransmission. However, there was some confusion in the conversation, and Pustogarov apologized for any misunderstandings. The attack discussed involves an attacker obtaining potential IP addresses of clients and spamming the network with this list. The attacker can clear the retransmission history by reconnecting after each spam round. This attack was described in detail on cryptolux.org and discussed on bitcointalk.org.Pustogarov proposed a solution to address this attack by periodically rotating outbound connections every 2-10 minutes. Each NATed client connects to the network through 8 entry peers and advertises its public IP address to them. An attacker can use this information to map out connections. However, Gregory Maxwell questioned Pustogarov's statement that an attacker with no peers would learn nothing about the Bitcoin network.The attack involves an attacker listening to transactions on the Bitcoin network and recording the first 8-10 peers that forward each transaction. This allows the attacker to link together different Bitcoin addresses and learn the IP of the client. The 8 entry peers are unique per client, so users sharing the same IP can be distinguished. Outbound connections are rotated from time to time due to remote disconnections, but the initial connections prefer nodes that were up recently.Pustogarov expressed concern about attackers without peers linking Bitcoin addresses and learning client IPs. The recipient of the email was confused about how this would be possible without any peers. Pustogarov explained that the unique 8 entry peers per client allow distinguishing users with the same IP. The discussion also touched on the rotation of outbound connections and the need for privacy through broadcasting over tor or i2p.In a Bitcoin-development mailing list conversation, Pustogarov proposed periodic rotation of outbound connections to improve network knowledge and make it stronger against partitioning. However, Maxwell disagreed, stating that constant outbound peers can prevent attackers from gaining strong evidence about transaction origin. It was recommended to broadcast over tor or i2p for privacy.Pustogarov initiated a discussion on the periodic rotation of outbound connections to improve network knowledge and make it stronger against partitioning. However, one recipient noted that rotating peers excessively is unnecessary and suggested broadcasting over tor or i2p for privacy.The periodic rotation of outbound connections aims to mitigate risks associated with 8 entry nodes uniquely identifying users. Attackers can link different blockchain addresses using this information. The proposed solution recommends periodic rotation to blur the fingerprint over time. Bitcoin clients advertise their public IP addresses, allowing attackers to deanonymize clients. The corresponding pull request is #4723, and more details can be found at cryptolux.org.In conclusion, Pustogarov's proposal for periodic rotation of outbound connections aims to address the risk of attackers linking Bitcoin addresses and learning client IPs. The discussion highlights the need for privacy through broadcasting over tor or i2p.
Updated on: 2023-08-01T10:14:21.742745+00:00