NOPF-core

Instead of connecting via port forwarding, connect using TCP hole punching.

Mechanism

• In order for a client to connect to the server, query each other's public IP, port from nopf-server.
• Using the obtained IP and port, the server first sends a SYN packet to the client.
• Even though the SYN packet is discarded by NAT/PAT on the client side, it is recorded on the server side.
• Because of recorded port, client can connect to server.
• Prevents ports from being cleared in NAT/PAT by blocking RST, FIN+ACK packets.

Usage

The process must proceed in this order: server inputs client's address -> client inputs server's address.
You should not input serveraddr with the same current public IP address

Usage: [-h --help] [-p --localport] [-a --serveraddr] [-t --type(server, s or not)]

--localport(-p)

• Case of server: port of your server local port
• Case of client: port to connect via localhost(you should connect to this port)

--serveraddr(-a)

nopf-server address

--type(-t)

• Case of server: input "s" or "server"
• Case of client: input other than "s" or "server"

Example

nopf-core server(localport:3000, serveraddr: 12.123.234.456:12345)

nopf-core> ./run.bat brun --localport=3000 --serveraddr=123.123.234.456:12345 --type=server
111.111.111.111:40737   (this is your public address and server's address)
222.222.222.222:64712     (input client's address first)
Started pipe between localhost:3000 - 222.222.222.222:64712 (it shows when a client is connected)

nopf-core client(localport:3010, serveraddr: 12.123.234.456:12345)

nopf-core> ./run.bat brun --localport=3010 --serveraddr=123.123.234.456:12345 --type=client
222.222.222.222:64712   (this is your public address and client's address)
111.111.111.111:40737     (input server's address last)
Started pipe between localhost:3010 - 111.111.111.111:40737 (it shows when you connect to localhost:3010)

See also: https://github.com/smiilliin/nopf-server

Development

you should install cmake, g++(mingw64), mingw-std-threads, windivert in windows

mingw-std-threads

https://github.com/meganz/mingw-std-threads

windivert

https://github.com/basil00/Divert

CMake

• ./run.bat debug: run cmake with debug mode
• ./run.bat release: run cmake with release mode

Build or Run

• ./run.bat build: build with g++
• ./run.bat run: run with g++
• ./run.bat brun: build and run