TCP hole punching for Bitcoin nodes behind home NATs?

The recent changes discussed in this pull request made the acceptance of inbound connections a default setting for Bitcoin nodes. This adjustment was motivated by the desire to increase the number of nodes that are accessible for incoming connections, thereby enhancing network robustness and connectivity.

To evaluate the impact of this change, it is suggested that updated measurements should be conducted to determine if any significant trends have emerged since the default setting was modified. Such data could reveal whether the network has become more open or if other factors have influenced node accessibility over time.

However, interpreting the results from these measurements requires caution. The presence of more reachable nodes on traditional ISPs compared to cloud services primarily reflects compatibility with routers and ISPs, rather than an explicit preference or consent from users regarding node reachability. Therefore, while technical factors may influence how many nodes can accept inbound connections, they do not necessarily indicate user intent concerning the public availability of their home nodes.