I have 2 computers behind NAT.
To make a connection between them I use an UDP hole punching protocol.
It works.
Now I want to send files by this tunnel. I guess I must have a TCP tunnel between those 2 computers.
Both firewall DENY all TCP trafic.
Is it possible ?
If not, is there any other solution ? How does Skype sends files by this UDP Tunnel ?
You can use UDT protocol for file transfer after it gets hole punched. UDT is made on top of UDP. It has the reliability of TCP and fastness of UDP.
UDT has an open source implementation.
来源：https://stackoverflow.com/questions/27842920/send-files-after-udp-hole-punching