Large-Scale Measurement of NAT Traversal for the Decentralized Web: A Case Study of DCUtR in IPFS
For researchers and developers of decentralized P2P systems, this work provides empirical benchmarks and insights into NAT traversal performance, though it is an incremental contribution as it validates existing protocols rather than introducing new methods.
This paper presents the first large-scale measurement study of the decentralized NAT traversal protocol DCUtR in IPFS, analyzing over 4.4 million attempts from 85,000+ networks. Key findings include a 70% success rate for hole-punching and that TCP and QUIC perform similarly, challenging the belief that UDP is superior for NAT traversal.
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 $70\% \pm 7.1\%$ 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 ($\sim70\%$). 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.