I2P Network Research Articles

Unveiling the I2P web structure: A connectivity analysis

Web is a primary and essential service to share information among users and organizations at present all over the world. Despite the current significance of such a kind of traffic on the Internet, the so-called Surface Web traffic has been estimated in just about 5% of the total. The rest of the volume of this type of traffic corresponds to the portion of the Web known as Deep Web. These contents are not accessible by usual search engines because they are authentication protected contents or pages only reachable through technologies denoted as darknets. To browse through darknet websites, special authorization or specific software and configurations are needed. TOR is one of the most used darknet nowadays, but there are several other alternatives such as I2P or Freenet, which offer different features for end users. In this work, we perform a connectivity analysis of the websites in the I2P network (named eepsites) aimed to discover if different patterns and relationships from those used in legacy webs are followed in I2P, as well as to get insights about the dimension and structure of this darknet. For that, a novel tool is specifically developed by the authors and deployed on a distributed scenario. Main results conclude the decentralized nature of the I2P network, where there is a structural part of interconnected eepsites while other several nodes are isolated probably due to their intermittent presence in the network.

Interconnection Between Darknets

Tor and i2p networks are two of the most popular darknets. Both darknets have become an area of illegal activities highlighting the necessity to study and analyze them to identify and report illegal content to Law Enforcement Agencies (LEAs). This paper analyzes the connections between the Tor network and the i2p network. We created the first dataset that combines information from Tor and i2p networks. The dataset contains more than 49k darknet services. The process of building and analyzing the dataset shows that it is not possible to explore one of the networks without considering the other. Both networks work as an ecosystem and there are clear paths between them. Using graph analysis, we also identified the most relevant domains, the prominent types of services in each network, and their relations. Findings are relevant to LEAs and researchers aiming to crawl and investigate i2p and Tor networks.

Deciding Your Own Anonymity: User-Oriented Node Selection in I2P

With the development of Internet applications, anonymous communication technology plays a very significant role in protecting personal privacy. As one of the most popular anonymous communication systems, I2P provides strong anonymity through its encryption and communication schemes. However, I2P does not consider the users’ preferences, which is difficult to meet the individual demands of specific users and then allows them to decide their anonymity. Thus, this paper proposes two novel user-oriented node selection algorithms that can effectively enhance the anonymity or reduce the communication delay over the I2P network. In order to choose proper nodes, we also investigate key factors to evaluate the nodes. Then, the basic node selection algorithm (BNSA) is proposed to group routing nodes and provide high-performance node candidates. Based on BNSA, the geographic-diversity-oriented node selection algorithm (GDNSA) and the communication-delay-oriented node selection algorithm (CDNSA) are proposed. These can improve the anonymity or communication performance of the I2P network. The GDNSA increases the attack difficulty by establishing tunnels that span multiple regions. In the meantime, the CDNSA reduces the communication delay of the tunnel by selecting the next hop node with the lowest communication delay. Finally, the mathematical analysis and experimental results show that the GDNSA has good resistance to collusion attacks, and the CDNSA reduces the communication delay in spite of weakening a little anonymity.

Empirical Measurement and Analysis of I2P Routers

With the increased focus on Internet privacy, especially after the exposure of PRISM(an Internet surveillance program), anonymous communication have been getting more and more attentions. One of the most widely used anonymous communication systems is I2P(Invisible Internet Project). And as opposed to Tor’s(another popular anonymous communication system) directory-based approach, which provides a centralized directory server to manage the overall ‘view’ of the network, I2P is fully distributed and self organizing, which aims to avoid attackers’ enumeration of all I2P’s routers. In this paper, based on I2P’s operating mechanism, we presented two passive and two active methods to discover I2P routers. In a more than two week’s collecting experiment, about 25640 routers were discovered everyday, which turned out to be an almost full coverage(94.9%) of the I2P network compared with the data announced on the official website [1]. And based on the routers collected, this paper further made a preliminary analysis of both the I2P network’s overall status and its security. The result showed that I2P is a well structured P2P network, while some powerful attackers operating several routers are still possible to perform compromise attack to break I2P users’ anonymity given the current I2P’s security mechanism. Finally, this paper discussed some countermeasures to improve the security of the I2P network.

Towards Measurement on the I2P Network

The I2P network has been widely used to protect user privacy via an open network of onion routers run by volunteers. To the best of our knowledge, the behavior of peers in the I2P network has not been well investigated in the existing researches. In this paper, we first present a simple and effective way to collect peers in the I2P network. Each day over 82% peers has been collected compared to the statistics from the statistics web site. With the data collected, we perform an empirical evaluation, revealing the phenomenon about IP address aliasing and identity aliasing. As identity aliasing makes bad impact on the availability and anonymity of the I2P network, we introduce family concept into the I2P network to mitigate the impact.