TopoShot: Uncovering Ethereum's Network Topology Leveraging Replacement Transactions

TL;DR

This paper introduces TopoShot, a novel method for measuring Ethereum network topology by leveraging transaction replacement policies, achieving high accuracy and revealing insights into network structure and centralization.

Contribution

TopoShot uniquely repurposes Ethereum's transaction eviction policies for accurate, scalable network topology measurement across various clients and networks.

Findings

Achieved 100% measurement precision and 88-97% recall.

Revealed full topology of major testnets and sub-networks in mainnet.

Identified centralization patterns in Ethereum network neighbor selection.

Abstract

Ethereum relies on a peer-to-peer overlay network to propagate information. The knowledge of Ethereum network topology holds the key to understanding Ethereum's security, availability, and user anonymity. From a measurement perspective, an Ethereum network's topology is routing-table information hidden inside individual Ethereum nodes, measuring which poses challenges and remains an open research problem in the existing literature. This paper presents TopoShot, a new method uniquely repurposing Ethereum's transaction replacement/eviction policies for topology measurement. TopoShot can be configured to support Geth, Parity, and other major Ethereum clients. As validated on local nodes, TopoShot achieves 100% measurement precision and high recall 88% - 97%. To efficiently measure the large Ethereum networks in the wild, we propose a non-trivial schedule to run pair-wise measurements in parallel. To enable ethical measurement on Ethereum mainnet, we propose workload-adaptive configurations of TopoShot to minimize the service interruption to target nodes/network. We systematically measure a variety of Ethereum networks and obtain new knowledge including the full-network topology in major testnets (Ropsten, Rinkeby and Goerli) and critical sub-network topology in the mainnet. The results on testnets show interesting graph-theoretic properties, such as all testnets exhibit graph modularity significantly lower than random graphs, implying resilience to network partitions. The mainnet results show biased neighbor selection strategies adopted by critical Ethereum services such as mining pools and transaction relays, implying a degree of centralization in real Ethereum networks.