I am experimenting with a file transfer program in Java and I wanted to create a server that would handle creating P2P connection between two clients.
Don't know how that should work, exchanging sockets? I don't want to exchange IP address... Seen some questions similar (ev. Connecting two clients via server java) but I have no idea how to achieve that. Thanks for your time
It sounds like you are looking for nat traversal techniques. There is no single solution because there are many different network setups. Most p2p software employs a combination of different solutions, such as using IPv6 where available, negotiating with home routers and operating system firewalls or NAT hole punching. Servers can assist in the last point.
来源：https://stackoverflow.com/questions/48508281/java-using-server-to-create-p2p-between-two-clients