I have found a new project which I have to say it's more powerfull than n2n

[LysLee111]

But the probrom is that its server is not open source, so it may contain a backdoor
Guys help me to check it:
https://github.com/openp2p-cn/openp2p

[eebssk1]

server side is open source(not full version)
https://github.com/openp2p-cn/gateway-lite

[sweihub]

The project is different from N2N, but I would suggest again N2N to utilize the public DHT network for hole-punching.