A comparative analysis of nat hole punching
Daniel Maier, Oliver Haase, Jürgen Wäsch, Marcel Waldvogel · KOPS (University of Konstanz) · 2011
IPv4’s address space is getting exhausted any day now. However, IPv6 is still only scarcely supported. Instead, the use of Network Address Translation (NAT) boxes to hide entire networks behind a single IPv4 address is the dominant solution. Increasingly interactive Internet applications prefer direct contacts, where a central server would only increase latency, limit throughput, or become a single point of failure. Direct connections are essential to such distinct applications ranging from interactive games and peer-to-peer applications to VoIP or file transfers among instant messaging partners. NAT Hole punching is one technique to traverse NAT boxes. It has the advantage of not requiring any user configuration and establishes direct connections between two peers without the need for additional relay servers. Hole punching is suitable for UDP and TCP. For TCP, two main options exist, namely sequential and parallel hole punching. These are the main targets of our analysis. We compare them according to various criteria in different scenarios.