TCP hole punching for Bitcoin nodes behind home NATs?

The exploration of pairing clearnet addresses with Tor service endpoints raises concerns about the potential for address correlation by adversaries, particularly when nodes also operate a P2P Tor service. The shutdown of such nodes might inadvertently increase the risk of correlating addresses. One proposed mitigation strategy involves synchronizing the creation of new Tor services with the generation of new ephemeral address messages, which could potentially reduce the likelihood of address correlation.

Additionally, the development of a TCP-like protocol over UDP, as discussed by programmers in the field, represents a significant technical challenge, albeit possibly less daunting than implementing multiprocess support currently being developed in Core. Despite the complexities, such a protocol could facilitate more efficient data transmission methods like compact block propagation by allowing packets to bypass certain traditional TCP constraints, such as strict ordering and stream semantics. This approach, although not widely adopted in adversarial settings, could provide substantial benefits if successfully implemented. The initial focus, however, should be on refining techniques such as TCP hole punching to enhance connectivity before advancing to more complex solutions.