Publications

IMC '26 Conference Paper · May 2026

Large-Scale Measurement of NAT Traversal for the Decentralized Web: A Case Study of DCUtR in IPFS

Dennis Trautwein · Cornelius Ihle · Moritz Schubotz · Corinna Breitinger · Bela Gipp

The promise of decentralized peer-to-peer (P2P) systems is fundamentally gated by the challenge of Network Address Translation (NAT) traversal, with existing solutions often reintroducing the very centralization they seek to avoid. This paper presents the first large-scale measurement study of a fully decentralized NAT traversal protocol, Direct Connection Upgrade through Relay (DCUtR), within the production libp2p-based InterPlanetary File System (IPFS) network. Drawing on over 4.4 million traversal attempts from 85,000+ distinct networks across 167 countries, we provide an empirical analysis of modern P2P connectivity. We establish a conditional success rate of 70% +- 7.1% for the hole-punching stage, given that prerequisite relay reservation and public address discovery succeed, providing a crucial new benchmark for the field. Critically, we empirically challenge the long-held belief of UDP's superiority for NAT traversal, demonstrating that DCUtR's high-precision, RTT-based synchronization yields statistically indistinguishable success rates for both TCP and QUIC (~70%). Our analysis further validates the protocol's design for permissionless environments by showing that success is independent of relay characteristics and that the mechanism is highly efficient, with 97.6% of successful connections established on the first attempt. Building on this analysis, we propose a concrete roadmap of protocol enhancements aimed at achieving universal connectivity and contribute our complete dataset to foster further research in this domain.

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University Other · Jan 2026

Measuring and Optimizing Peer-to-Peer Networks: A Case Study of the InterPlanetary File System

Dennis Trautwein

The Internet's transformation from a decentralized network of networks into a landscape dominated by centralized platforms has created systemic risks including infrastructure fragility, censorship vulnerabilities, and concentrated control. While decentralized peer-to-peer systems offer architectural alternatives, they suffer from a fundamental architectural knowledge imbalance: centralized platforms observe all user interactions enabling sophisticated optimization, whereas peer-to-peer networks lack unified observability, hindering both performance analysis and targeted improvements. This dissertation addresses this challenge through comprehensive characterization and optimization of the InterPlanetary File System (IPFS), a prominent peer-to-peer storage network. IPFS's hybrid architecture of combining peer-to-peer networking with strategic centralized components creates fragmented visibility where different subsystems offer complementary but partial vantage points. The research develops measurement methodologies that synthesize these fragmented observations into comprehensive network understanding. It then leverages empirical insights for a targeted protocol optimization. The investigation spans three critical measurement domains. Network topology and content routing performance characterization identified Distributed Hash Table publication latency as the critical bottleneck, with median latencies of 27.7 seconds from Europe. Peer connectivity and Network Address Translation traversal measurements through a novel honeypot methodology established a 70% success rate for decentralized hole-punching across 4.4 million measurements from 167 countries and 85k networks. Usage patterns and content governance analysis revealed a concentration-replication duality where single peers hosted up to 63% of denylist content yet widespread replication ensured only 0.1% of content remained uniquely hosted, complicating coordinated takedown efforts. IPFS' systematic characterization enabled the design and deployment of Optimistic Provide, a backward-compatible protocol optimization achieving order-of-magnitude performance improvements: sub-second publication latency for 90% of operations while reducing network overhead by 40%. The research demonstrates that systematic synthesis of partial observations can overcome the architectural knowledge imbalance, enabling evidence-based optimizations that enhance peer-to-peer systems' viability as alternatives to centralized architectures.

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MIDDLEWARE '25 Conference Paper · Dec 2025

PANDAS: Peer-to-peer, Adaptive Networking Allowing Data Availability Sampling within Ethereum Consensus Timebounds

Matthieu Pigaglio · Onur Ascigil · Michał Król · Felix Lange · Kaleem Peeroo · Sergi Rene · Ramin Sadre · Vladimir Stankovic · Etienne Rivière

Layer-2 protocols such as rollups can help address Ethereum's throughput limits. An efficient data availability layer is key for layer-2 support in Ethereum, but broadcast methods do not scale. A promising approach is the selective distribution of layer-2 data and its verification by data availability sampling (DAS). Integrating DAS with Ethereum consensus is, however, a challenge, as data must be shared and sampled within 4 seconds of each consensus slot. We propose PANDAS, a practical approach to integrating DAS with Ethereum without modifying Ethereum's core protocols. PANDAS disseminates layer-2 data and samples its availability using lightweight, direct exchanges. Its design accounts for message loss, node failures, and unresponsive participants. Our evaluation in a 1,000-node cluster and simulations for up to 20,000 peers show that PANDAS allows layer-2 data dissemination and sampling under planetary-scale latencies within the 4-second deadline.

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SIGMETRICS '26 Conference Paper · Dec 2025

Multiple Sides of 36 Coins: Measuring Peer-to-Peer Infrastructure Across Cryptocurrencies

Lucianna Kiffer · Lioba Heimbach · Dennis Trautwein · Yann Vonlanthen · Oliver Gasser

Blockchain technologies underpin an expanding ecosystem of decentralized applications, financial systems, and infrastructure. However, the fundamental networking layer that sustains these systems, the peer-to-peer (P2P) layer, of all but the top few ecosystems remains largely opaque. In this paper, we present the first longitudinal, cross-network measurement study of 36 public blockchain networks. Over 9 months (since late 2024), we deployed 15 active crawlers, sourced data from two additional community crawlers, and conducted hourly connectivity probes (e.g., pings and protocol-level handshakes) to observe the evolving state of these networks. Furthermore, by leveraging Ethereum's discovery protocols, we inferred metadata for an additional 19 auxiliary networks that utilize the Ethereum peer discovery protocol. We also explored Internet-wide scans, which only require probing each protocol's default ports with a simple, network-specific payload. This approach allows us to rapidly identify responsive peers across the entire address space without having to implement custom discovery and handshake logic for every blockchain. We validated this method on Bitcoin and similar networks with known ground truth, then applied it to Cardano, which we could not crawl directly. Our study uncovers dramatic variation in network size from under 10 to more than 10,000 active nodes. We quantify trends in IPv4 versus IPv6 usage, analyze autonomous systems and geographic concentration, and characterize churn, diurnal behavior, and the coverage and redundancy of discovery protocols. These findings expose critical differences in network resilience, decentralization, and observability. Beyond characterizing each network, our methodology demonstrates a general framework for measuring decentralized networks at scale. This opens the door for continued monitoring, benchmarking, and more transparent assessments of blockchain infrastructure across diverse ecosystems.

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EthResearch Technical Report · Jun 2025

Impact of IDONTWANT in the Number of Duplicates

Mikel Cortes · Yiannis Psaras

This Ethereum Research study analyzes the impact of the IDONTWANT message primitive on reducing duplicate message propagation in Ethereum's Gossipsub network following its adoption during the Pectra upgrade (with ~95% network adoption by May 2025). The research found that while IDONTWANT does provide modest improvements for larger messages like beacon blocks and blobs—increasing messages with zero duplicates from 2% to 9% and reducing average duplicates from 3 to 2—its effectiveness is significantly limited because approximately 70% of observed duplicates still arrive after IDONTWANT messages are sent, indicating that messages are already in transit by the time the control notification reaches peers. The study identified additional inefficiencies, including duplicates resulting from IWANT requests (~29% of cases) where nodes request messages that have already begun downloading, and instances where some protocol implementations fail to respect IDONTWANT signals and continue transmitting messages anyway. The researchers recommend improvements such as limiting IWANT message frequency, delaying initial IWANT requests to avoid requesting messages that are already arriving, ensuring implementations cancel IWANT replies upon receiving IDONTWANT, and fixing cases where published messages queued for transmission aren't cancelled when IDONTWANT is received.

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Springer Cluster Computing Journal Article · Jun 2025

The Impact of Connectivity and Software in Ethereum Validator Performance

Mikel Cortes-Goicoechea · Tarun Mohandas-Daryanani · Jose Luis Muñoz-Tapia · Leonardo Bautista-Gomez

Modern public blockchains like Ethereum rely on p2p networks to run distributed and censorship-resistant applications. With its wide adoption, it operates as a highly critical public ledger. On its transition to become more scalable and sustainable, shifting to PoS without sacrificing the security and resilience of PoW, Ethereum offers a range of consensus client implementations to participate in the network. In this paper, we present a methodology to measure the performance of the consensus clients based on the latency to receive messages from the p2p network. The paper includes a study that identifies the incentives and limitations that the network experiences, presenting insights about the latency impact derived from running the different consensus implementations at different locations. Our study highlights the need for a holistic approach to node deployment, where hardware, software, and geographic factors have to be carefully considered. Properly dimensioned hardware is essential to mitigate latency-related performance issues and ensure the reliable operation of beacon nodes, especially in geographically distant locations.

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EthResearch Technical Report · May 2025

Empirical Blob Sidecar Hit Rate Based on Local EL’s Mempool

Mikel Cortes · Yiannis Psaras

This empirical study measures blob sidecar availability in Ethereum's execution layer (EL) mempool to assess the feasibility of distributed block building for reducing validator bandwidth requirements. Analyzing data from both pre- and post-Pectra periods (which increased blob targets from 3 to 6 and maximum from 6 to 9), the researchers found a high empirical blob hit-rate where 76.6% of engine API requests successfully retrieved all requested blob sidecars from the local EL mempool within 100 milliseconds, with 98% of partial responses missing only a single blob sidecar. The study reveals that most blob sidecars are already present in the EL by the time blocks are broadcast on the consensus layer, indicating that the network is currently generating significant redundant traffic in blob propagation. While this redundancy provides resilience, it also represents a bottleneck and inefficiency; the authors recommend exploring alternatives such as shifting blob sharding to the EL layer and implementing a "Blob mempool DHT" proposal to enable more efficient network resource utilization and reduce the time pressure on consensus layer blob broadcasting.

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EthResearch Technical Report · Apr 2025

Theoretical Blob Hit Rate Based on the EL Mempool

Mikel Cortes · Yiannis Psaras

This theoretical analysis by Mikel Cortes and Yiannis Psaras from ProbeLab examines blob transaction hit rates in Ethereum's execution layer (EL) mempool to assess the feasibility of distributed block-building as a mechanism to reduce bandwidth burdens on validators who build blocks locally. Using data from the public Xatu database spanning March 1-15, 2025, the study demonstrates that blob transactions achieve high visibility across the network with 99% propagating within one second across geographically dispersed regions. Key findings show that 81.91% of proposed blob transactions are available in the public mempool before the slot in which they are included, with only 4.12% arriving after slot start, and 75.11% of blocks have all their blob transactions present in the EL mempool at the time of proposal. The results indicate that distributed block-building is theoretically viable at current blob transaction rates, though the analysis also reveals that the network currently propagates redundant information by broadcasting blob transactions first through the EL mempool and then rebroadcasting sidecars over the consensus layer's GossipSub topics, while approximately 14.76% of proposed blob transactions originate from private mempools.

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IEEE Access V12 Journal Article · Mar 2025

Can We Run Our Ethereum Nodes at Home?

Mikel Cortes-Goicoechea · Tarun Mohandas-Daryanani · Jose Luis Muñoz-Tapia · Leonardo Bautista-Gomez

Scalability is a common issue among the most used permissionless blockchains, and several approaches have been proposed to solve it. However, tackling scalability while preserving the security and decentralization of the network is a significant challenge. To deliver effective scaling solutions, Ethereum achieved a significant protocol improvement, including a change in the consensus mechanism towards Proof of Stake. This improvement greatly reduced the hardware requirements to run a node, leading to significant sustainability benefits with a lower network energy consumption. This work analyzes the resource usage behaviour of different clients running as Ethereum consensus nodes, comparing their performance under different configurations and analyzing their differences. Our results show higher requirements than initially claimed and show how different clients react to network perturbations. Furthermore, we discuss the differences between the consensus clients, including their strong points and limitations.

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EthResearch Technical Report · Dec 2024

Bandwidth Availability in Ethereum: Regional Differences and Network Impacts

Mikel Cortes · Yiannis Psaras

This comprehensive bandwidth availability study by Mikel Cortes and Yiannis Psaras from ProbeLab measures the capacity of Ethereum nodes to handle increased blob propagation by analyzing data from 9,179 nodes across four geographical regions (California, Virginia, Frankfurt, and Sydney) over six days in November 2024. Using a custom tool called "net-probe" that saturates nodes' uplinks through block-by-range RPC calls, the researchers found significant geographical disparities in available bandwidth: 60% of nodes in Europe and North America exceed 20 Mbps upload capacity, while only 20% of Australian nodes achieve this threshold due to the distribution of 65% of Ethereum's nodes in the US and Europe. The study demonstrates that bandwidth availability drops 9-13% during the first four seconds of each slot when blocks and blobs are broadcast, yet nodes still maintain 18-23 Mbps of mean available capacity during these critical periods. The analysis of blob distribution during the measurement period shows 35% of slots contained no blobs and 42% contained 5-6 blobs, while cloud-hosted nodes demonstrated approximately 5 Mbps more available bandwidth than non-cloud deployments. The authors conclude that the proposed increase in blob target and maximum values from 3/6 to 6/9 represents a reasonable adjustment given current network capacity, though they emphasize the importance of implementing bandwidth-saving improvements such as PeerDAS and modified Gossipsub protocols for future scalability.

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BIOTC '24 Conference Paper · Oct 2024

An Analytical Study of Large Blocks on Ethereum

Patrick Ocheja · Mikel Cortes-Goicoechea · Tarun Mohandas-Daryanani · Brendan Flanagan · Hiroaki Ogata · Jose Luis Munoz · Leonardo Bautista-Gomez

Ethereum's application layer data, especially the analysis of large blocks, holds critical insights into its network dynamics and future developments. In this study, we systematically analyze various components of this data, including blocks, transactions, gas prices, and address interactions. This study places a significant emphasis on systematically analyzing Ethereum blocks of size 500KB and above, a crucial element considering the impending Ethereum Improvement Proposals (EIPs) like EIP4844. EIP4844 proposes the introduction of a new type of data, known as "blob data" specifically designed to be used in rollups, which are off-chain aggregation of transactions within a single on-chain transaction. Our analysis includes blocks, transactions, gas prices, and address interactions, with a special focus on the characteristics and implications of large block sizes. We observe notable trends such as block fullness, transaction count fluctuations, and gas price variations. Importantly, our findings reveal that a substantial number of Ethereum blocks exceed the expected size of 1.875MB, reaching up to 2MB. This is particularly relevant in the context of EIP4844, as many of these large blocks might be related to rollup data, which is a cornerstone of Ethereum's scalability strategy. We also discovered a moderate negative correlation between block sizes and number of transactions contained in them. Similarly, average daily gas prices tend to decrease with an increase in block sizes. These insights are invaluable for the blockchain community, offering guidance to developers and users for optimizing transaction strategies and managing costs in anticipation of future network changes. Our study not only contributes to a deeper understanding of Ethereum's current state but also provides a foundational analysis for assessing the impact of rollups and other scalability solutions on Ethereum's evolving ecosystem.

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BIOTC '24 Conference Paper · Oct 2024

Scalability Limitations of Kademlia DHTs when Enabling Data Availability Sampling in Ethereum

Mikel Cortes-Goicoechea · Csaba Kiraly · Dmitriy Ryajov · Jose Luis Muñoz-Tapia · Leonardo Bautista-Gomez

Scalability in blockchain remains a significant challenge, especially when prioritizing decentralization and security. The Ethereum community has proposed comprehensive data-sharding techniques to overcome storage, computational, and network processing limitations. In this context, the propagation and availability of large blocks become the subject of research to achieve scalable data-sharding. This paper provides insights after exploring the usage of a Kademlia-based Distributed Hash Table (DHT) to enable Data Availability Sampling (DAS) in Ethereum. It presents a DAS-DHT simulator to study this problem and validates the results of the simulator with experiments in a real DHT network, InterPlanetary File System (IPFS). Our results help us understand what parts of DAS can be achieved based on existing Kademlia DHT solutions and which ones cannot. We discuss the limitations of DHT solutions and discuss other alternatives.

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University Other · Sep 2024

A Deep Dive into Ethereum's PoS Transition: Protocol Design Choices and their Empirical Unexpected Limitations

Mikel Cortes-Goicoechea

The advent of the internet, marked by pivotal developments such as the launch of Arpanet and the standardization of HTTP, has irrevocably changed the fabric of modern society. Centralized platforms like Microsoft, Google, Apple, and Amazon have dominated this digital landscape, offering many services ranging from cloud computing to online storage. However, the centralized nature of these services has raised significant concerns regarding user privacy, data integrity, and the potential for censorship. In response to these issues, the open-source community has explored peer-to-peer alternatives, notably in the realm of distributed file systems, ledgers, and blockchain technology. Blockchains, popularized by the emergence of Bitcoin, promote a democratized service model that challenges the centralized status quo. Yet, they are not without their own challenges, including decentralization, security, privacy, and performance. This thesis delves into the nuances of blockchain technology, focusing on Ethereum's transition from Proof of Work (PoW) to Proof of Stake (PoS) and its implications on network hardware requirements, topology, and overall performance. The development of Ethereum serves as a small-scale reflection of the broader ambitions and challenges in transitioning to Decentralized Finance (DeFi) platforms. Despite significant theoretical advancements in consensus mechanisms and scalability solutions, real-world implementations and experimental validations remain sparse. This work aims to bridge this gap by comprehensively analysing Ethereum's PoS transition by examining the interlaced relationships between software logic, hardware configurations, and network dynamics. Through novel measurement models and tools, this thesis contributes to a deeper understanding of how Ethereum's architectural changes impact its ecosystem and its participants' behaviours. Lastly, the research presented in this thesis illustrates the technical and operational challenges facing Ethereum and similar blockchain platforms and proposes a series of contributions that advance the field. This work empirically analyses the future enhancements in blockchain technology by exploring the implications of the network and its topology, to the viability of decentralized validation processes, and the potential for scaling solutions like Data Availability Sampling. The open-source tools and methodologies developed within the thesis scope represent the commitment to transparency and collaboration, which follows the spirit of the decentralized communities it seeks to serve. Through a mix of theoretical exploration and empirical research, this thesis aims to provide a deeper and more detailed understanding of Ethereum PoS' design choices, its capabilities and the limitations this one represents in future steps and upgrades, leading the way for more resilient, scalable, and decentralized digital infrastructures.

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Usenix Sec '24 Conference Paper · Aug 2024

Guardians of the Galaxy: Content Moderation in the InterPlanetary File System

Saidu Sokoto · Leonhard Balduf · Dennis Trautwein · Yiluo Wei · Gareth Tyson · Ignacio Castro · Onur Ascigil · George Pavlou · Maciej Korczyński · Björn Scheuermann · Michał Król

The Interplanetary File System (IPFS) is one of the largest platforms in the growing "Decentralized Web". The increasing popularity of IPFS has attracted large volumes of users and content. Unfortunately, some of this content could be considered "problematic". Content moderation is always hard. With a completely decentralized infrastructure and administration, content moderation in IPFS is even more difficult. In this paper, we examine this challenge. We identify, characterize, and measure the presence of problematic content in IPFS (e.g. subject to takedown notices). Our analysis covers 368,762 files. We analyze the complete content moderation process including how these files are flagged, who hosts and retrieves them. We also measure the efficacy of the process. We analyze content submitted to denylist, showing that notable volumes of problematic content are served, and the lack of a centralized approach facilitates its spread. While we identify fast reactions to takedown requests, we also test the resilience of multiple gateways and show that existing means to filter problematic content can be circumvented. We end by proposing improvements to content moderation that result in 227% increase in the detection of phishing content and reduce the average time to filter such content by 43%.

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EuroS&P '24 Conference Paper · Jul 2024

DISC-NG: Robust Service Discovery in the Ethereum Global Network

Michał Król · Onur Ascigil · Sergi Rene · Alberto Sonnino · Matthieu Pigaglio · Ramin Sadre

The Ethereum Global Network (EGN) hosts a complete ecosystem of decentralized services, including blockchains such as Ethereum mainnet but also exchange markets, content delivery networks, and many more. Service discovery is a fundamental mechanism in the EGN, allowing new nodes to look up and connect to other nodes already participating in one of these services. The current service discovery of the EGN, DISCv5, is not scalable and efficient enough to support the current and future needs of the ecosystem. We present DISC-NG, a novel service discovery protocol for the EGN that is scalable, efficient, and secure. DISC-NG leverages the EGN-wide DHT to allow service participation advertisements to meet service discovery requests. DISC-NG compensates the unbalance in service popularity and minimizes the potential for abuse by malicious nodes. We implement DISC-NG in devp2p, the network stack used by the majority of clients connecting to the EGN, as well as in a large-scale simulator. DISC-NG can discover services in the EGN faster than DISCv5 while being more robust to malicious nodes. DISC-NG is now in a staging phase and scheduled for deployment as an improvement to DISCv5.

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EthResearch Technical Report · Jul 2024

Gossipsub Message Propagation Latency

Mikel Cortes · Yiannis Psaras

This message propagation latency study by Yiannis Psaras and Mikel Cortes from ProbeLab investigates how quickly GossipSub delivers blocks across Ethereum's peer-to-peer network using data from three days of measurements (June 14-16) from the Ethereum Foundation's Xatu monitoring nodes deployed across three continents (Europe, North America, and Australia) running all major consensus clients. The analysis reveals that 98% of beacon blocks arrive within the critical 4-second propagation window required to prevent network forks, though a small fraction of outliers arrive as late as 12 seconds. Examination of per-client performance shows distinct patterns, with Teku and Prysm nodes receiving messages fastest while Lodestar exhibits the longest arrival times and highest variance, though the authors note these differences may relate to how different implementations timestamp message arrivals in their validation logic. Geographic analysis demonstrates that European nodes enjoy a modest ~0.6-second latency advantage over North American and Oceanian nodes, highlighting a slight centralization incentive toward lower-latency network core regions, though current differences remain within acceptable safety margins. The study finds no significant correlation between block size (mostly 50-150 KB) and arrival time, and concludes that despite these minor geographic and client-based differences, message propagation latency is generally well-controlled and sufficient to maintain network stability.

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EthResearch Technical Report · Jul 2024

Ethereum Node Message Propagation Bandwidth Consumption

Mikel Cortes · Yiannis Psaras

This bandwidth consumption analysis by Yiannis Psaras and Mikel Cortes from ProbeLab investigates the GossipSub protocol components responsible for message propagation bandwidth usage in Ethereum's peer-to-peer network using the Hermes monitoring tool. Analyzing a 3.5-hour trace of GossipSub traffic, the study reveals that sent messages (SENT_MSG) consume the largest share at 53% of total bandwidth (69% of outbound), followed surprisingly by control messages, with SENT_IHAVE messages accounting for 23.4% of total bandwidth and 30% of outbound traffic, and received IHAVE messages representing 10% of total bandwidth and 42% of inbound traffic. The analysis shows that IHAVE and IHAVE-related control traffic consumes approximately 400 KB/s collectively, representing a major optimization opportunity, while received duplicates account for 7.3% of total bandwidth compared to only 3.6% for original messages. The study validates findings from prior research on IHAVE/IWANT effectiveness and emphasizes that duplicates collectively represent approximately 42% of total bandwidth consumption. The authors project that standard Ethereum nodes consume approximately 386 KB/s inbound and 580 KB/s outbound (including execution layer), and strongly recommend adoption of GossipSub 1.2 to eliminate duplicate message bandwidth, as this would provide significant network-wide efficiency gains while remaining a small fraction of typical household bandwidth availability.

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EthResearch Technical Report · Jun 2024

Number Duplicate Messages in Ethereum’s Gossipsub Network

Mikel Cortes · Yiannis Psaras

This duplicate message analysis by Yiannis Psaras from ProbeLab investigates the prevalence and characteristics of duplicate messages in Ethereum's GossipSub network using the Hermes monitoring tool over a 3.5-hour period on Holesky testnet. The study establishes a theoretical framework predicting that with a mesh degree (k) of 8, nodes should receive approximately 3 duplicates per message (calculated as (k-2)/2), and confirms this for certain message types while revealing significant variations across different topics: beacon_block messages show almost no non-duplicated instances (1-2%) with 54% receiving the expected 3 duplicates but outliers reaching 34-40 copies, while smaller, more frequent messages like beacon_aggregate_and_proof show 32-45% with no duplicates and 50% with fewer than 2 duplicates. The analysis finds no correlation between message size and duplicate count, and reveals a critical temporal pattern where 50% of duplicate arrivals occur within 73 milliseconds of the original message, enabling potential optimization. The study identifies that numerous duplicates originate from IWANT messages sent milliseconds before the same message arrives through mesh propagation, leading to two key recommendations: implementing a concurrency limiter on IWANT messages (similar to Kademlia's alpha parameter) and increasing the heartbeat interval from 0.7 to 1.0 seconds to reduce excessive IHAVE messages and duplicate-generating race conditions. The authors conclude that GossipSub 1.2's proposed IDONTWANT control message would be valuable for preventing the majority of duplicates.

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EthResearch Conference Paper · Jun 2024

Gossipsub Network Dynamicity through GRAFTs and PRUNEs

Mikel Cortes · Yiannis Psaras

This network dynamicity study by Yiannis Psaras from ProbeLab analyzes GossipSub's mesh stability by investigating GRAFT and PRUNE message frequencies, session durations, and network stability through a 3.5-hour trace using the Hermes monitoring tool on Holesky testnet. The analysis reveals that despite increased dynamicity observed through GRAFT and PRUNE events, GossipSub successfully maintains stable mesh topology with the number of mesh peers per topic consistently remaining between the DLow (6) and DHigh (12) thresholds around the target of 8 peers. The study finds that 80% of peer connections are relatively short (dropping within seconds), while 10% persist for approximately 4 minutes and the remaining 10% maintain connections from 5 minutes to 1.6 hours; notably, Lodestar and Nimbus clients maintain significantly longer connection durations compared to Teku nodes, which consistently disconnect almost immediately. A notable spike in GRAFT and PRUNE events occurs during the final hour of the measurement period, with subsequent analysis identifying this as stemming from GossipSub peer scoring mechanisms responding to peers forwarding invalid messages on the voluntary_exit topic. The authors conclude that while the Hermes node observes elevated mesh connectivity dynamics, GossipSub maintains a healthy mesh structure with stable peer degrees despite these fluctuations, and the observed anomalies do not appear to impact broader network operation.

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EthResearch Technical Report · May 2024

Gossip IWANT/IHAVE Effectiveness in Ethereum’s Gossipsusb Network

Mikel Cortes · Yiannis Psaras

This study by Yiannis Psaras from ProbeLab examines the efficiency of Gossipsub's IHAVE/IWANT control message mechanism in Ethereum's peer-to-peer network using the custom-built Hermes monitoring tool, which traces all GossipSub protocol interactions. Based on a 3.5-hour trace of network activity, the research reveals that the gossip mechanism is substantially inefficient, with ratios of sent IHAVE message IDs to received IWANT message IDs reaching approximately 1:100 for beacon blocks, 1:10 for beacon aggregate and proofs, and 1:6 for sync committee contributions—indicating that over 10 times more bandwidth is consumed by control messages than what is actually needed. The analysis shows that IHAVE and IWANT messages serve different purposes depending on message type: less frequent large messages (like beacon blocks) rely primarily on mesh propagation and receive minimal benefit from gossip, while very frequent small messages incur substantial control message overhead. The study identifies implementation anomalies in Teku nodes that send IHAVE and IWANT messages with empty topics, and proposes three optimization directions: replacing message ID lists with bloom filters, reducing the GossipsubHistoryGossip parameter from 3 to 2 heartbeats, and implementing adaptive GossipFactor per topic to balance bandwidth efficiency with network robustness. The authors emphasize that while IHAVE/IWANT mechanisms are essential for network resilience during attacks and anomalies, significant optimization potential exists under normal operating conditions.

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INFOCOM '24 Conference Paper · May 2024

IPFS in the Fast Lane: Accelerating Record Storage with Optimistic Provide

Dennis Trautwein · Yiluo Wei · Yiannis Psaras · Moritz Schubotz · Ignacio Castro · Bela Gipp

The centralization of web services has raised concerns about critical single points of failure, such as content hosting, name resolution, and certification. To address these issues, the "Decentralized Web" movement advocates for de-centralized alternatives. Distributed Hash Tables (DHTs) have emerged as a key component facilitating this movement, as they offer efficient key/value indexing. The InterPlanetary File System (IPFS) exemplifies this approach by leveraging DHTs for data indexing and distribution. A critical finding of previous studies is that DHT PUT performance for record storage is unacceptably slow, sometimes taking minutes to complete and hindering the adoption of delay-intolerant applications. To address this challenge, this research paper presents three significant contributions. First, we present the design of Optimistic Provide, an approach to accelerate DHT PUT operations in Kademlia-based IPFS networks while maintaining full backward compatibility. Second, we implement and deploy the mechanism and see its usage in the de-facto IPFS deployment, Kubo. Third, we evaluate its effectiveness in the IPFS and Filecoin DHTs. We confirm that we enable sub-second record storage from North America and Europe for 90% of PUT operations while reducing networking overhead by over 40% and maintaining record availability.

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NSDI '24 Conference Paper · Apr 2024

The Eternal Tussle: Exploring the Role of Centralization in IPFS

Yiluo Wei · Dennis Trautwein · Yiannis Psaras · Ignacio Castro · Will Scott · Aravindh Raman · Gareth Tyson

Web centralization and consolidation has created potential single points of failure, e.g., in areas such as content hosting, name resolution, and certification. The "Decentralized Web", led by open-source software implementations, attempts to build decentralized alternatives. The InterPlanetary File System (IPFS) is part of this effort and attempts to provide a decentralized layer for object storage and retrieval. This comes with challenges, though: Decentralization can increase complexity, overhead, as well as compromise performance and scalability. As the core maintainers of IPFS, we have therefore begun to explore more hybrid approaches. This paper reports on our experiences building three centralized components within IPFS: (i) InterPlanetary Network Indexers, which provides an alternative centralized method for content indexing; (ii) Hydra Boosters, which are strategic DHT nodes that assist IPFS in content routing; and (iii) HTTP Gateways, which are a public access point for users to retrieve IPFShosted content. Through this approach, we trade-off the level of decentralization within IPFS in an attempt to gain certain benefits of centralization. We evaluate the performance of these components and demonstrate their ability to successfully address the challenges that IPFS faces.

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NDSS '24 Conference Paper · Feb 2024

Content Censorship in the InterPlanetary File System

Srivatsan Sridhar · Onur Ascigil · Navin Keizer · François Genon · Sébastien Pierre · Yiannis Psaras · Etienne Rivière · Michał Król

The InterPlanetary File System (IPFS) is currently the largest decentralized storage solution in operation, with thousands of active participants and millions of daily content transfers. IPFS is used as remote data storage for numerous blockchain-based smart contracts, Non-Fungible Tokens (NFT), and decentralized applications. We present a content censorship attack that can be executed with minimal effort and cost, and that prevents the retrieval of any chosen content in the IPFS network. The attack exploits a conceptual issue in a core component of IPFS, the Kademlia Distributed Hash Table (DHT), which is used to resolve content IDs to peer addresses. We provide efficient detection and mitigation mechanisms for this vulnerability. Our mechanisms achieve a 99.6% detection rate and mitigate 100% of the detected attacks with minimal signaling and computational overhead. We followed responsible disclosure procedures, and our countermeasures are scheduled for deployment in the future versions of IPFS.

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BCCA '23 Conference Paper · Oct 2023

Unveiling Ethereum's Hidden Centralization Incentives: Does Connectivity Impact Performance?

Mikel Cortes-Goicoechea · Tarun Mohandas-Daryanani · Jose Luis Munoz-Tapia · Leonardo Bautista-Gomez

Modern public blockchains like Ethereum rely on p2p networks to run distributed and censorship-resistant applications. With its wide adoption, it operates as a highly critical public ledger. On its transition to become more scalable and sustainable, shifting to PoS without sacrificing the security and resilience of PoW,Ethereum offers a range of consensus clients to participate in the network. In this paper, we present a methodology to measure the performance of the consensus clients based on the latency to receive messages from the p2p network. The paper includes a study that identifies the incentives and limitations that the network experiences, presenting insights about the latency impact derived from running the software in different locations.

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CSUR '23 Journal Article · Jul 2023

Incentive Mechanisms in Peer-to-Peer Networks – A Systematic Literature Review

Cornelius Ihle · Dennis Trautwein · Moritz Schubotz · Norman Meuschke · Bela Gipp

Centralized networks inevitably exhibit single points of failure that malicious actors regularly target. Decentralized networks are more resilient if numerous participants contribute to the network’s functionality. Most decentralized networks employ incentive mechanisms to coordinate the participation and cooperation of peers and thereby ensure the functionality and security of the network. This article systematically reviews incentive mechanisms for decentralized networks and networked systems by covering 165 prior literature reviews and 178 primary research papers published between 1993 and October 2022. Of the considered sources, we analyze 11 literature reviews and 105 primary research papers in detail by categorizing and comparing the distinctive properties of the presented incentive mechanisms. The reviewed incentive mechanisms establish fairness and reward participation and cooperative behavior. We review work that substitutes central authority through independent and subjective mechanisms run in isolation at each participating peer and work that applies multiparty computation. We use monetary, reputation, and service rewards as categories to differentiate the implementations and evaluate each incentive mechanism’s data management, attack resistance, and contribution model. Further, we highlight research gaps and deficiencies in reproducibility and comparability. Finally, we summarize our assessments and provide recommendations to apply incentive mechanisms to decentralized networks that share computational resources.

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arxiv Preprint · Jun 2023

Data Availability Sampling in Ethereum: Analysis of P2P Networking Requirements

Michał Król · Onur Ascigil · Sergi Rene · Etienne Rivière · Matthieu Pigaglio · Kaleem Peeroo · Vladimir Stankovic · Ramin Sadre · Felix Lange

Despite their increasing popularity, blockchains still suffer from severe scalability limitations. Recently, Ethereum proposed a novel approach to block validation based on Data Availability Sampling (DAS), that has the potential to improve its transaction per second rate by more than two orders of magnitude. DAS should also significantly reduce per-transaction validation costs. At the same time, DAS introduces new communication patterns in the Ethereum Peer-to-Peer (P2P) network. These drastically increase the amount of exchanged data and impose stringent latency objectives. In this paper, we review the new requirements for P2P networking associated with DAS, discuss open challenges, and identify new research directions.

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ICBC '23 Conference Paper · May 2023

Autopsy of Ethereum's Post-Merge Reward System

Mikel Cortes-Goicoechea · Tarun Mohandas-Daryanani · Jose Luis Muñoz-Tapia · Leonardo Bautista-Gomez

Like most modern blockchain networks, Ethereum has relied on economic incentives to promote honest participation in the chain's consensus. The distributed character of the platform, together with the “randomness” or “luck” factor that both proof of work (PoW) and proof of stake (PoS) provide when electing the next block proposer, pushed the industry to model and improve the reward system of the system. With several improvements to predict PoW block proposal rewards and to maximize the extractable rewards of the same ones, the ultimate Ethereum's transition to PoS applied in the Paris Hard-Fork, more generally known as “The Merge”, has meant a significant modification on the reward system in the platform. In this paper, we aim to break down both theoretically and empirically the new reward system in this post-merge era. We present a highly detailed description of the different rewards and their share among validators' rewards. Ultimately, we offer a study that uses the presented reward model to analyze the performance of the network during this transition.

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IEEE Spectrum v59 Journal Article · Nov 2022

To the InterPlanetary File System–and Beyond!: Peer-to-peer file sharing would make the Internet far more efficient

Yiannis Psaras · Jorge M. Soares · David Dias

When the COVID-19 pandemic erupted in early 2020, the world made an unprecedented shift to remote work. As a precaution, some Internet providers scaled back service levels temporarily, although that probably wasn't necessary for countries in Asia, Europe, and North America, which were generally able to cope with the surge in demand caused by people teleworking (and binge-watching Netflix). That's because most of their networks were overprovisioned, with more capacity than they usually need. But in countries without the same level of investment in network infrastructure, the picture was less rosy: Internet service providers (ISPs) in South Africa and Venezuela, for instance, reported significant strain.

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IEEE Internet Computing Journal Article · Sep 2022

Toward Decentralized Cloud Storage With IPFS: Opportunities, Challenges, and Future Considerations

Trinh Viet Doan · Yiannis Psaras · Jörg Ott · Vaibhav Bajpai

The InterPlanetary File System (IPFS) is a novel decentralized storage architecture, which provides decentralized cloud storage by building on founding principles of P2P networking and content addressing. IPFS is used by more than 230k peers per week and serves tens of millions of requests per day, which makes it an interesting large-scale operational network to study. While it is used as a building block in several projects and studies, its inner workings, properties, and implications have only been marginally explored in research. Thus, we provide an overview of the IPFS design and its core features, along with the opportunities that it opens, as well as the challenges that it faces because of its properties. Overall, IPFS presents an interesting set of characteristics and offers lessons that can help build decentralized systems of the future.

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SIGCOMM '22 Conference Paper · Aug 2022

Design and Evaluation of IPFS: A Storage Layer for the Decentralized Web

Dennis Trautwein · Aravindh Raman · Gareth Tyson · Ignacio Castro · Will Scott · Moritz Schubotz · Bela Gipp · Yiannis Psaras

Recent years have witnessed growing consolidation of web operations. For example, the majority of web traffic now originates from a few organizations, and even micro-websites often choose to host on large pre-existing cloud infrastructures. In response to this, the "Decentralized Web" attempts to distribute ownership and operation of web services more evenly. This paper describes the design and implementation of the largest and most widely used Decentralized Web platform - the InterPlanetary File System (IPFS) - an open-source, content-addressable peer-to-peer network that provides distributed data storage and delivery. IPFS has millions of daily content retrievals and already underpins dozens of third-party applications. This paper evaluates the performance of IPFS by introducing a set of measurement methodologies that allow us to uncover the characteristics of peers in the IPFS network. We reveal presence in more than 2700 Autonomous Systems and 152 countries, the majority of which operate outside large central cloud providers like Amazon or Azure. We further evaluate IPFS performance, showing that both publication and retrieval delays are acceptable for a wide range of use cases. Finally, we share our datasets, experiences and lessons learned.

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ICDCSW '22 Conference Paper · Jul 2022

Enriching Kademlia by Partitioning

João Monteiro · Pedro Ákos Costa · João Leitão · Alfonso De la Rocha · Yiannis Psaras

Decentralizing the Web is becoming an increasingly interesting endeavor that aims at improving user security and privacy as well as providing guaranteed ownership of content. One such endeavor that pushes towards this reality, is Protocol Labs' Inter-Planetary File System (IPFS) network, that provides a decentralized large scale file system to support the decentralized Web. To achieve this, the IPFS network leverages the Kademlia DHT to route and store pointers to content stored by network members (i.e., peers). However, due to the large number of network peers, content, and accesses, the DHT routing needs to be efficient and quick to enable a decentralized web that is competitive. In this paper, we present work in progress that aims at improving the Kademlia DHT performance through the manipulation of DHT identifiers by adding prefixes to identifiers. With this, we are able to bias the DHT topological organization towards locality (which can be either geographical or applicational), which creates partitions in the DHT and enables faster and more efficient query resolution on local content. We designed prototypes that implement our proposal, and performed a first evaluation of our work in an emulated network testbed composed of 5000 nodes. Our results show that our proposal can benefit the DHT look up on data with locality with minimal overhead.

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CoNEXT-SW '21 Workshop Paper · Dec 2021

Leveraging Node Heterogeneity to Improve Content Discovery and Content Retrieval in Peer-to-Peer Networks

Dennis Trautwein · Moritz Schubotz · Bela Gipp

Distributed content-addressed networks like the Interplanetary File System (IPFS) have gained popularity in recent years. It is used as a data storage layer for Blockchain applications or generally as a censorship-resistant file-sharing network. In the past, many traditional peer-to-peer networks eventually implemented super-peer sub-topologies within their otherwise nonhierarchical network to increase the efficiency of various system tasks. While it can be observed that IPFS also holds such tendencies, no formalism supports these developments. This article will present a research project that will investigate if and how a super-peer architecture can complement the IPFS network from a content discovery and retrieval perspective. Further, first preliminary results on peer churn rate in the IPFS and Filecoin networks will be discussed.

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TON '21 Journal Article · Nov 2021

A Congestion Control Framework Based on In-Network Resource Pooling

Sergi Rene · Onur Ascigil · Yiannis Psaras · George Pavlou

Congestion control has traditionally relied on monitoring packet-level performance (e.g., latency, loss) through feedback signals propagating end-to-end together with various queue management practices (e.g., carefully setting various parameters, such as router buffer thresholds) in order to regulate traffic flow. Due to its end-to-end nature, this approach is known to transfer data according to the path’s slowest link, requiring several RTTs to transmit even a few tens of KB during slow start. In this paper, we take a radically different approach to control congestion, which obviates end-to-end performance monitoring and careful setting of network parameters. The resulting In-Network Resource Pooling Protocol (INRPP) extends the resource pooling principle to exploit in-network resources such as router storage and unused bandwidth along alternative sub-paths. In INRPP, content caches or large (possibly bloated) router buffers are used as a place of temporary custody for incoming data packets in a store and forward manner. Data senders push data in the network and when it hits the bottleneck link, in-network caches at every hop store data in excess of the link capacity; nodes progressively move/send data (from one cache to the next) towards the destination. At the same time alternative sub-paths are exploited to move data faster towards the destination. We demonstrate through extensive simulations that INRPP is TCP friendly, and improves flow completion time and fairness by as much as 50% compared to RCP, MPTCP and TCP, under realistic network conditions.

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AFT '21 Conference Paper · Nov 2021

Shard Scheduler: Object Placement and Migration in Sharded Account-Based Blockchains

Michał Król · Onur Ascigil · Sergi Rene · Alberto Sonnino · Mustafa Al-Bassam · Etienne Rivière

We propose Shard Scheduler, a system for object placement and migration in account-based sharded blockchains. Our system calculates optimal placement and decides on object migrations across shards. It supports complex multi-account transactions caused by smart contracts. Placement and migration decisions made by Shard Scheduler are fully deterministic, verifiable, and can be made part of the consensus protocol. Shard Scheduler reduces the number of costly cross-shard transactions, ensures balanced load distribution and maximizes the number of processed transactions for the blockchain as a whole. To this end, it leverages a novel incentive model motivating miners to maximize the global throughput of the entire blockchain rather than the throughput of a specific shard. In our simulations, Shard Scheduler can reduce the number of costly cross-shard transactions by half while ensuring equal load and increasing throughput more than 2 fold when using 60 shards. We also implement and evaluate Shard Scheduler on Chainspace, more than doubling its throughput and reducing user-perceived latency by 70% when using 10 shards.

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BCCA '21 Conference Paper · Nov 2021

Discovering the Ethereum2 P2P Network

Mikel Cortes-Goicoechea · Leonardo Bautista-Gomez

Achieving the equilibrium between scalability, sustainability, and security while keeping decentralization has prevailed as the target solution for decentralized blockchain applications over the last years. Several approaches have been proposed by multiple blockchain teams to achieve it, Ethereum being among them. Ethereum is on the path of a major protocol improvement called Ethereum 2.0 (Eth2), implementing Sharding and introducing the Proof-of-Stake (PoS). As the change of consensus mechanism is a delicate matter, this improvement will be achieved through different phases, the first of which is the implementation of the Beacon Chain. As Ethereum1, Eth2 relies on a decentralized peer-to-peer (p2p) network for the message distribution. Up to date, we estimate that there are around 5.000 nodes in the Eth2 main net geographically distributed. However, the topology of this one still prevails unknown. In this paper, we present the results obtained from the analysis we performed on the Eth2 p2p network. Describing the topology of the network, as possible hazards that this one implies.

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BRAINS '21 Conference Paper · Sep 2021

Resource Analysis of Ethereum 2.0 Clients

Mikel Cortes · Luca Franceschini · Leonardo Bautista-Gomez

Scalability is a common issue among the most used permissionless blockchains, and several approaches have been proposed to solve this issue. Tackling scalability while preserving the security and decentralization of the network is an important challenge. To deliver effective scaling solutions, Ethereum is on the path of a major protocol improvement called Ethereum 2.0 (Eth2), which implements sharding. As the change of consensus mechanism is an extremely delicate matter, this improvement will be achieved through different phases, the first of which is the implementation of the Beacon Chain. For this, a specification has been developed, and multiple groups have implemented clients to run the new protocol. This work analyzes the resource usage behavior of different clients running as Eth2 nodes, comparing their performance and analyzing differences. Our results show multiple important network perturbations and how different clients react to them. We discuss the differences between Eth2 clients and their limitations.

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ICBC '21 Conference Paper · Jun 2021

FLOCK: Fast, Lightweight, and Scalable Allocation for Decentralized Services on Blockchain

Navin V. Keizer · Onur Ascigil · Yiannis Psaras · George Pavlou

Many decentralized services have recently emerged on top of blockchain, offering benefits like privacy, and allowing any node in the network to share its resources. In order to be a competitive alternative to their central counterparts, their performance needs to match up. Specifically, service allocation remains a performance bottleneck for many decentralized services.In this paper we present FLOCK, an allocation system which is highly scalable, fast, and lightweight. Furthermore, it allows nodes to indicate their preference for clients/sellers without needing to submit bids by using stable matching algorithms. We decouple the price discovery and outsource this function to a smart contract on the blockchain.Additionally, another smart contract is used to orchestrate the allocation and take care of service discovery, while trusted execution environments securely compute allocation solutions, and off-chain payment networks are used to send rewards.Evaluation of FLOCK shows that gas costs are manageable and improve upon other solutions which leverage auctions, and that our instance of the stable matching algorithm greatly improves run-time and throughput over auction counterparts. Finally, our discussion outlines practical improvements to further increase performance.

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IFIP '21 Conference Paper · Jun 2021

The Case for AI Based Web3 Reputation Systems

Navin V. Keizer · Fan Yang · Yiannis Psaras · George Pavlou

Initiatives such as blockchains and decentralized storage networks are pushing for a decentralized Web3 to replace the current architecture. At the core of Web3 are network resource sharing services, which allow anyone to sell spare network capacity in return for rewards. These services require a way to establish trust, as parties are potentially malicious. This can be achieved by reputation systems. In this paper we make the case for using deep reinforcement learning in Web3 reputation calculation. More specifically, we propose a model which allows for decentralized calculation of scores with high personalization for the user.

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IFIP '21 Conference Paper · Jun 2021

IPFS-FAN: A Function-Addressable Computation Network

Alfonso de la Rocha · Yiannis Psaras · David Dias

Permissionless computation is one of the missing pieces in the web3 stack in order to have all the tools needed to “decentralise Internet services”. There are already proposals to embed computation in decentralised networks like smart contracts, or blockchain networks for computational offloading. Although technically sound, their computational model is too restrictive to be used for general purpose computation. In this paper, we propose a general architecture of a decentralised network for general-purpose and permissionless computation based on content-addressing. We present a proof-of-concept prototype and describe in detail its building blocks.

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IFIP '21 Conference Paper · Jun 2021

Introducing Peer Copy – A Fully Decentralized Peer-to-Peer File Transfer Tool

Dennis Trautwein · Moritz Schubotz · Bela Gipp

Peer Copy is a decentralized, peer-to-peer file transfer tool based on libp2p. It allows any two parties that are either both on the same network or connected via the internet to transfer the contents of a file based on a particular sequence of words. Peer discovery happens via multicast DNS if both peers are on the same network or via entries in the distributed hash table (DHT) of the InterPlanetary File-System (IPFS) if both peers are connected across network boundaries. As soon as a connection is established, the word sequence is used as the input for a password-authenticated key exchange (PAKE) to derive a strong session key. This session key authenticates the peers and encrypts any subsequent communication. It is found that the decentralized approach to peer-to-peer file transfer can keep up with established centralized tools while eliminating the reliance on centralized service providers.

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TOIT '21 Conference Paper · Jun 2021

Proof-of-Prestige: A Useful Work Reward System for Unverifiable Tasks

Michał Król · Alberto Sonnino · Mustafa Al-Bassam · Argyrios G. Tasiopoulos · Etienne Rivière · Yiannis Psaras

As cryptographic tokens and altcoins are increasingly being built to serve as utility tokens, the notion of useful work consensus protocols is becoming ever more important. With useful work consensus protocols, users get rewards after they have carried out some specific tasks useful for the network. While in some cases the proof of some utility or service can be provided, the majority of tasks are impossible to verify reliably. To deal with such cases, we design “Proof-of-Prestige” (PoP)—a reward system that can run directly on Proof-of-Stake (PoS) blockchains or as a smart contract on top of Proof-of-Work (PoW) blockchains. PoP introduces “prestige,” which is a volatile resource that, in contrast to coins, regenerates over time. Prestige can be gained by performing useful work, spent when benefiting from services, and directly translates to users minting power. Our scheme allows us to reliably reward decentralized workers while keeping the system free for the end-users. PoP is resistant against Sybil and collusion attacks and can be used with a vast range of unverifiable tasks. We build a simulator to assess the cryptoeconomic behavior of the system and deploy a full prototype of a content dissemination platform rewarding its participants. We implement the blockchain component on both Ethereum (PoW) and Cosmos (PoS), provide a mobile application, and connect it with our scheme with a negligible memory footprint. Finally, we adapt a fair exchange protocol allowing us to atomically exchange files for rewards also in scenarios where not all the parties have Internet connectivity. Our evaluation shows that even for large Ethereum traces, PoP introduces sub-millisecond computational overhead for miners in Cosmos and less than 0.013$ smart contract invocation cost for users in Ethereum.

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ResNetLab Technical Report · Jan 2021

Accelerating Content Routing with Bitswap: A multi-path file transfer protocol in IPFS and Filecoin

Alfonso de la Rocha · David Dias · Yiannis Psaras

Bitswap is a Block Exchange protocol designed for P2P Content Addressable Networks. It leverages merkle-linked graphs in order to parallelize retrieval and verify content integrity. Bitswap is being used in the InterPlanetary File System architecture as the main content exchange protocol, as well as in the Filecoin network as part of the block synchronisation protocol. In this work, we present Bitswap’s baseline design and then apply several new extensions with the goal of improving Bitswap’s efficiency and efficacy and minimizing its bandwidth fingerprint. Most importantly, our extensions result in a substantial increase to the protocol’s content discovery rate. This is achieved by using the wealth of information that the protocol acquires from the content routing subsystem to make smarter decisions on where to fetch the content from.

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Mobihoc '20 Conference Paper · Oct 2020

Rewarding Relays for Decentralised NAT Traversal using Smart Contracts

Navin V. Keizer · Onur Ascigil · Yiannis Psaras · George Pavlou

Traversing NAT's remains a big issue in P2P networks, and many of the previously proposed solutions are incompatible with truly decentralised emerging applications. Such applications need a decentralised NAT traversal solution without trusted centralised servers. In this paper we present a decentralised, relay-based NAT traversal system, where any reachable node is able to assist an unreachable node in NAT traversal. Smart contracts on the Ethereum blockchain are used to ensure fair rewards. Besides financial incentives, a reputation system based on transactions on-chain is used to mitigate against malicious behaviour, and guide peer discovery. Evaluation of our system shows that a combination of historic performance metrics leads to an optimal scoring function, that the system takes little time to reach stability from inception, and that the system is resilient against various attacks. Implementation of the smart contract shows that the cost for participants is manageable.

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arXiv Preprint · Jul 2020

GossipSub: Attack-Resilient Message Propagation in the Filecoin and ETH2.0 Networks

Dimitris Vyzovitis · Yusef Napora · Dirk McCormick · David Dias · Yiannis Psaras

Permissionless blockchain environments necessitate the use of a fast and attack-resilient message propagation protocol for Block and Transaction messages to keep nodes synchronised and avoid forks. We present GossipSub, a gossip-based pubsub protocol, which, in contrast to past pubsub protocols, incorporates resilience against a wide spectrum of attacks. Firstly, GossipSub's mesh construction implements an eager push model keeps the fan-out of the pubsub delivery low and balances excessive bandwidth consumption and fast message propagation throughout the mesh. Secondly, through gossip dissemination, GossipSub realises a lazy-pull model to reach nodes far-away or outside the mesh. Thirdly, through constant observation, nodes maintain a score profile for the peers they are connected to, allowing them to choose the most well-behaved nodes to include in the mesh. Finally, and most importantly, a number of tailor-made mitigation strategies designed specifically for these three components make GossipSub resilient against the most challenging Sybil-based attacks. We test GossipSub in a testbed environment involving more than 5000 VM nodes deployed on AWS and show that it stays immune to all considered attacks. GossipSub is currently being integrated as the main messaging layer protocol in the Filecoin and the Ethereum 2.0 (ETH2.0) blockchains.

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IFIP '20 Conference Paper · Jun 2020

The InterPlanetary File System and the Filecoin Network

Yiannis Psaras · David Dias

The InterPlanetary File System (IPFS) is a peer-to-peer content-addressable distributed file system that seeks to connect all computing devices with the same system of files. It is an open-source community-driven project, with reference implementations in Go and Javascript, and a global community of millions of users. IPFS and libp2p, which is the modular network stack of IPFS, are based on name-resolution based routing. The resolution system is based on Kademlia DHT and content is addressed by flat hash-based names. IPFS sees significant real-world usage, with over 250,000 daily active network nodes, millions of end users and wide adoption by several other projects in the Decentralised Web space, but not only. An adjacent project to IPFS, which was also masterminded and is also being developed within Protocol Labs (the umbrella company of IPFS and libp2p) is filecoin. Filecoin is a token protocol that supports a decentralised storage network. Storage miners are rewarded according to their contribution to the network and the mechanics of filecoin secure the network against malicious activity. The objective of this half-day tutorial is to make the audience familiar with IPFS and filecoin and able to use the tools provided by the project for research and development. The tutorial targets both developers and researchers, who may contribute to the project or use it as a tool.

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ICN '19 Conference Paper · Sep 2019

Towards Peer-to-Peer Content Retrieval Markets: Enhancing IPFS with ICN

Onur Ascigil · Sergi Reñé · Michał Król · George Pavlou · Lixia Zhang · Toru Hasegawa · Yuki Koizumi · Kentaro Kita

In the current Internet, content delivery, e.g., video-on-demand (VoD), at scale is associated with a large distributed infrastructure which requires considerable investment. Content Providers (CPs) typically resort to third-party Content Distribution Networks (CDNs) or build their own expensive content delivery infrastructure in order to cope with the peak demand and maintain sufficient quality-of-service (QoS), while Internet Service Providers (ISPs) need to overprovision their networks. In this paper we take a first step towards designing a system that uses storage space of users as CDN caches and deliver content with sufficient (i.e., CDN-like) quality while rewarding users for their resource usage as in a content retrieval marketplace. As a possible candidate for such a system, we consider recent P2P storage and delivery systems that have adopted new mechanisms such as rewarding of useful work (e.g., storage) while ensuring fairness and accountability through cryptographic proofs. In this paper, we experiment with the popular Interplanetary File System (IPFS) and investigate its performance in delivering VoD content locally within an ISP. Our findings suggest that operating IPFS (operating on top of IP) has its performance limitations and complementing it with an ICN network layer can significantly improve the delivery quality. We then propose and compare several forwarding strategies for ICN which can efficiently route requests and balance the load between peers with limited uplink resources.

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