P2P-Over-MiddleBoxes-Demo

A simple demo of P2P communication over middle boxes such as NAT

p2pchat

build:

make p2pchat

run:

./p2pchat/server port

./p2pchat/client server:port
>>> help

test

build:

make test

run:

./run_test.sh

FAQ

It doesn't work?

This UDP hole punching demo only works on Cone NAT.

How to check my NAT type?

There is a simple python script to test your NAT type using RFC3489(the classic STUN protocol) in stun. You can simply check it by running:

cd stun
python3 classic_stun_client.py [your-local-ip]

And the result would be similar with:

INFO:root:running test I with stun.ideasip.com:3478
INFO:root:MAPPED_ADDRESS: 220.181.57.217:46208
INFO:root:running test II with stun.ideasip.com:3478
INFO:root:running test I with 217.116.122.138:3479
INFO:root:MAPPED_ADDRESS: 220.181.57.217:2732
NAT_TYPE: Symmetric NAT

My NAT is cone NAT, but it still doesn't work

If two of your peers are both behind the same NAT, this NAT must support LOOPBACK TRANSMISSION to forward messages. You can test it by using the utils(udp_server/udp_client) in tools

related post (in Chinese)

• https://www.pppan.net/blog/detail/2017-12-16-p2p-over-middle-box(up to date)
• http://jekyll.pppan.net/2015/10/31/p2p-over-middle-box/(original post)

NOTE: This is just a proof of concept project. If you want to build a stable P2P application, please refer to STUN/TURN and ICE protocol as well.