# TxProbe: Discovering Bitcoin's Network Topology Using Orphan Transactions

## TL;DR

TxProbe is a novel method that leverages orphan transaction peculiarities to accurately reconstruct Bitcoin's network topology, aiding measurement and analysis efforts.

## Contribution

The paper introduces TxProbe, a new technique for revealing Bitcoin's network topology by exploiting orphan transaction processing behaviors.

## Key findings

- Achieves over 90% precision and recall in topology reconstruction.
- Can quickly snapshot Bitcoin testnet topology within hours.
- Demonstrates effectiveness on Bitcoin testnet experiments.

## Abstract

Bitcoin relies on a peer-to-peer overlay network to broadcast transactions and blocks. From the viewpoint of network measurement, we would like to observe this topology so we can characterize its performance, fairness and robustness. However, this is difficult because Bitcoin is deliberately designed to hide its topology from onlookers. Knowledge of the topology is not in itself a vulnerability, although it could conceivably help an attacker performing targeted eclipse attacks or to deanonymize transaction senders. In this paper we present TxProbe, a novel technique for reconstructing the Bitcoin network topology. TxProbe makes use of peculiarities in how Bitcoin processes out of order, or "orphaned" transactions. We conducted experiments on Bitcoin testnet that suggest our technique reconstructs topology with precision and recall surpassing 90%. We also used TxProbe to take a snapshot of the Bitcoin testnet in just a few hours. TxProbe may be useful for future measurement campaigns of Bitcoin or other cryptocurrency networks.