🔒 How to make a simple connection between a host and client on the same internet provider ?

[rare cloud]

import socket as S

HOST = "0.0.0.0"
PORT = 10

def server():
    server = S.socket(S.AF_INET, S.SOCK_STREAM)
    server.bind((HOST, PORT))
    server.listen()
    running = True
    while running:
        client, adress = server.accept()
        print("connecte avec", str(adress))
        client.send("hello".encode("utf-8"))
        
def client():
    cli = S.socket(S.AF_INET, S.SOCK_STREAM)
    while True:
        print("connect")
        cli.connect((HOST, PORT))
        cli.send("yo je suis client".encode("utf-8"))
        sleep(1)
        
        
if __name__ == "__main__":
    server()
    # client(), for client

Hi, using Socket, i want to make a connection between two machine by the simlpest way possible. I made the python script above, my problem is that nothing happend. Is it a python issue ? machine issue ? how should i make this ?
Thanks.

[fast drift]

@rare cloud

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[rare cloud]

when running the client script, i input my public IPv4 adress as HOST

[hybrid swift]

i'm guessing you are running the two functions on two different machines?

[rare cloud]

is there a diference ? would it work using 2 machines ? and witch way to connect to internet shold i use ?

for now, i'm running two scripts on the same machine

[lucid steppe]

How do you know nothing happens? Both sides send, but neither receives.

[hybrid swift]

the important thing is that there is actual connectivity between the machines, this shouldn't be a problem if you're running the two instances on the same machine

[lucid steppe]

0.0.0.0 is ok for the server to listen on everything. But you need a specific IP address for the client to use. Though you said you were doing that.

[rare cloud]

is my public IPv4 the right one ?

[lucid steppe]

If you're using the same machine you could use 127.0.0.1 (localhost). Get things working. Then use public addresses.

[hybrid swift]

you probably want to start with 127.0.0.1 which is local host if you are running both functions on the same machine to start with

[lucid steppe]

When you say public, do you mean the LAN address (oten 192.168.* or 172.16.*) or a genuine public address routable from the public internet?

[hybrid swift]

i'm guessing your computer doesn't have your public ip (out on the internet) directly attached, right?

[lucid steppe]

Hey, is this on a UNIX machine? Or Linux? You won't be allowed to use port 10. You will need a number over 1024. Probably well over 1024, since many low ports are in use.

Like 9999.

[rare cloud]

i'm on windows

[lucid steppe]

You may be fine with 10 then. Unsure.

Provided it's not already in use.

[hybrid swift]

yeah, port 10 can be an issue

unless running the script with administrator privileges on the system (which you shouldn't unless absolutely necessary)

[lucid steppe]

I assume your script is silent? Not raising an exception.

[rare cloud]

cli.connect(("127.0.0.1", PORT))
ConnectionRefusedError: [WinError 10061] No connection could be established because the target computer specifically refused it

what does this error mean ? is this a windows issue ?

hmm my bad, the server was'nt running

[hybrid swift]

most systems will not let you bind the server process to a port under 1024 without administrator privileges

so pick a port over that if you can

[rare cloud]

ok it works using the same machine

[hybrid swift]

and then it's the issue if the server isn't running or hasn't been able to bind to the port that you ask it to bind to (either because of missing privileges or that something else is already using that port, as each port can only be used by one process at a time)

great!

just know that you can also have issues with the windows firewall stopping connections

or if you have any other security software that runs its own firewall that can also become a problem

[rare cloud]

how do i make it to work on different machine using diferent internet providers ?

[hybrid swift]

first if you are on the same local network you would use your LAN (Local Area Network) internal ip address to reach the server machine instead of 127.0.0.1

then if we are talking about connectivity over the internet, then you need to either have the server directly on the public ip address or forward a port from a firewall/router to the machine on the internal network running the server software

or you will need to use a service such as ngrok or similar to expose the service to the internet through this service

if the server should not be exposed to the whole internet you can setup a priivate proxy or network service such as tailscale or twingate or similar

[rare cloud]

ok, i will try this later (i'm in CS course), thanks !!!

[hybrid swift]

good luck with your little project

[fast drift]

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