Challenging Tribal Knowledge -- Large Scale Measurement Campaign on Decentralized NAT Traversal

TL;DR

This study provides the first large-scale empirical analysis of decentralized NAT traversal, revealing new benchmarks, refuting assumptions about protocol superiority, and suggesting improvements for universal connectivity in P2P networks.

Contribution

It offers the first comprehensive measurement of a fully decentralized NAT traversal protocol, establishing new success benchmarks and challenging existing beliefs about protocol performance.

Findings

70% success rate for NAT traversal with 7.1% variance

TCP and QUIC have statistically similar success rates

97.6% of connections succeed on the first attempt

Abstract

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, longitudinal measurement study of a fully decentralized NAT traversal protocol, Direct Connection Upgrade through Relay (DCUtR), within the production libp2p-based IPFS network. Drawing on over 4.4 million traversal attempts from 85,000+ distinct networks across 167 countries, we provide a definitive empirical analysis of modern P2P connectivity. We establish a contemporary baseline success rate of $70\% \pm 7.1\%$ for the hole-punching stage, providing a crucial new benchmark for the field. Critically, we empirically refute the long-held 'tribal knowledge' 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 ($\sim70\%$). 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.