NAT punch-through on mobile network for p2p model?

Question

I am writing a p2p messaging Android app, and I'm trying to solve the problem of NAT on mobile networks. I cannot currently find a way for a device to connect to another listening device on a 3G/4G network due to the carrier's NAT service.

I have heard of a few NAT punch-through methods, but a lot of those involve using some sort of centralized server as a mediator. I am trying to use a completely decentralized p2p approach to accomplish this task.

Are there any feasible ways of allowing a device on a mobile network to be publicly addressable?

Thanks!

Answer 1

No, it is not possible. Most of the time, subscribers with IP addresses NATed are behind NAT444 and many subscribers are anycasted ( subscribers have the same IP on their mobile phone, but nated behind a different NAT devices). And 2 anycasted suscribers cannot communicate together.

The only way left you is to open a VPN to get a real IP of Internet Public.

My suggestion would be: Do not use VPN for IPv4 ! Use VPN to get a real IPV6 to your mobile phone application, and build your p2p application over IPv6.

You are fighting with very old problem that drove IETF to build IPv6.

So, go to IPv6, and forget ipv4. The ONLY good solution for your problem is to build your app over IPv6, and your app has to bring the ipv6 tunnel to the phone.