STUN and TURN were already mentioned. There is also Apple's own NAT-PMP which is more like UPnP but simpler. It can directly ask your (Apple) router to open a

STUN and TURN were already mentioned. There is also Apple's own NAT-PMP which is more like UPnP but simpler. It can directly ask your (Apple) router to open a port and redirect it incoming traffic to a specific IP address on your local network. https://secure.wikimedia.org/wikipedia/en/wiki/NAT_Port_Mapping_Protocol https://secure.wikimedia.org/wikipedia/en/wiki/NAT_Port_Mapp... I bet Apple also supports UPnP these days.