TCP穿孔（旁路监听套接字）

Question

现在,我可以通过NAT建立连接,但只能使用连接套接字：

A.connect(B) -> Crash agains't B's NAT, but open a hole in A's NAT.
B.connect(A) -> Get in A's NAT hole, reach A's connecting socket.

但现在，发送SYN数据包进行连接的两个套接字已经连接。

你会认为我会做的，通过两个NATs得到一个连接，万岁。

#!/usr/bin/env python3
from socket import *
from threading import Thread
Socket = socket

# The used endpoints:
LOCAL = '0.0.0.0', 7000
REMOTE = 'remote', 7000

# Create the listening socket, bind it and make it listen:
Listening = Socket(AF_INET, SOCK_STREAM)
Listening.setsockopt(SOL_SOCKET, SO_REUSEADDR, 1)
Listening.bind(LOCAL)
Listening.listen(5)

# Just start in another thread some kind of debug:
# Print the addr of any connecting client:
def handle():
    while not Listening._closed:
        client, addr = Listening.accept()
        print('ACCEPTED', addr)
Thread(target=handle).start()

# Now creating the connecting socket:
Connecting = Socket(AF_INET, SOCK_STREAM)
Connecting.setsockopt(SOL_SOCKET, SO_REUSEADDR, 1)
Connecting.bind(LOCAL)

# Now we can attempt a connection:
try:
    Connecting.connect(REMOTE)
    print('CONNECTED', Connecting.getpeername())
except Exception as e:
    print('TRIED', type(e), e)

Answer 1

所以，经过更多的测试和阅读，我得出了以下结论：

实际上，可以将侦听套接字和进行出站连接的套接字绑定在同一地址(ip，端口）上。

但套接字的行为严重依赖于系统/TCP堆栈的实现,如http://www.brynosaurus.com/pub/net/p2pnat/at§4.3: