java - Android: NAT Traversal?

Question

It appears to me that newer Android devices run behind a NAT, where the local address is an internal carrier or LAN address and the public address is the router or carrier assigned external address.

Nevertheless, newer phones don't return the same address using the NetworkInterface as when accessing an IP detection service.

Therefore, connecting via direct P2P SocketChannels inherently fails.

Are there any common workarounds to this problem designed for the Android platform? Can anyone clarify what is causing this NAT-like security issue?

Any links to Java NAT traversal tutorials or examples (NOT essays or theses) would also be appreciated as being helpful (as I'm not quite sure how to implement it in Java).

I will of course also accept any other solutions anyone has to offer!

Answer 1

Almost every phone or PC you will ever touch won't have a static public IP address, and therefore will require NAT traversal. It's not because of the device; the carrier or ISP put routers between your device and the public internet. Depending on your application, usually there are NAT-traversal libraries you can use, such as ice4j or STUNT.