Further reading

Further reading

Wikipedia: A list of every NAT traversal method

• There are a few options I don't personally recommend, such as TCP hole punching or UPnP, due to the former not working for some and the latter being not safe + requiring special setup, essentially as much setup as port forwarding requires. However this page summarizes things very well, and lists a lot of other options you can try.

YouTube:

Multiplayer without a server using UDP holepunching

• A decent video from an indie game dev

How NAT Saved the Internet (from IPV4 saturation)

• General NAT explanation

Simultaneous open - TCP without a server

• Awesome video, fine on the security front- however I recommend not using this anymore as it didn't work for some users, due to System.currentTimeMillis() being out of sync between some users, and some other users' wifi networks not supporting TCP hole punching.

• However it's a cool technique for learning purposes only, and it's what I to get the original demo in pure Java to work. The deleted file named SimplerExample.java in the repository history contains two examples in 300 and 50 lines.