python socket not connecting to web server

Question

I'm trying use the python socket module to connect to an ngrok server. If I put the ngrok into my browser it connects properly so the problem is somewhere with my client code. Here is the server code:

#server.py
import socketserver
class MyTCPHandler(socketserver.BaseRequestHandler):
    def handle(self):
        self.data = self.request.recv(1024).strip()
        print("{} wrote:".format(self.client_address[0]))
        print(self.data)
if __name__ == "__main__":
    HOST, PORT = "192.168.86.43", 8080
    server = socketserver.TCPServer((HOST, PORT), MyTCPHandler)
    server.serve_forever()

And here is the client:

#client.py
import socket
with socket.socket(socket.AF_INET, socket.SOCK_STREAM) as sock:
    sock.connect(("http://urlhere.ngrok.io", 8080))
    sock.sendall(bytes("Hello" + "\n", "utf-8"))

Thanks!

Answer 1

In general you should be able to connect to any globally available address or DNS name, ensuring there is no network restrictions on the way. However you have to listen on the address that is locally available for global routing if you are communicating across the Internet.

As for particular code, there are 2 issues:

1. Socket should be connected to an address or DNS name. The protocol is defined with the socket type. In your case

import socket
with socket.socket(socket.AF_INET, socket.SOCK_STREAM) as sock:
    sock.connect(("localhost", 8080))
    sock.sendall(bytes("Hello" + "\n", "utf-8"))

2. You're binding in the server to some speciffic not related address. To run your code you should bind to either localhost or to "any available" address "0.0.0.0":

import socketserver
class MyTCPHandler(socketserver.BaseRequestHandler):
    def handle(self):
        self.data = self.request.recv(1024).strip()
        print("{} wrote:".format(self.client_address[0]))
        print(self.data)
if __name__ == "__main__":
    HOST, PORT = "0.0.0.0", 8080
    server = socketserver.TCPServer((HOST, PORT), MyTCPHandler)
    server.serve_forever()