Comment by ignoramous
9 hours ago
> really wish there was a standardized way to do it. Some sort of explicit (or at least implicit but unambiguous) indicator to all firewalls that a connection from a given host/port pair is desired for the next few seconds
NAT Behavioural Requirements for Unicast UDP, https://datatracker.ietf.org/doc/html/rfc4787
NAT Behavioural Requirements for TCP, https://datatracker.ietf.org/doc/html/rfc5382
> NAT Behavioural Requirements for TCP
TIL, thank you! I've been looking for this for quite a while after hearing it indirectly referenced recently, but only found host-side specifications for TCP simultaneous open.
Do you happen to know if common firewalls and NATs support it? If they do, I really wonder why TCP hole punching isn't more common.