I'm just trying to get a very basic websocket connection over internet. The code seems fine - because it works when connecting to localhost - but for some reason fails when I try to use it over the internet. I'm using the websockets library, and my server looks like this:
#!/usr/bin/env python3
import asyncio
import websockets
from logging import getLogger, INFO, StreamHandler
logger = getLogger('websockets')
logger.setLevel(INFO)
logger.addHandler(StreamHandler())
clients = set()
async def handler(websocket, path):
global clients
clients.add(websocket)
try:
await asyncio.wait([ws.send("Hello!") for ws in clients])
await asyncio.sleep(10)
finally:
clients.remove(websocket)
start_server = websockets.serve(handler, host='127.0.0.1', port=6969)
asyncio.get_event_loop().run_until_plete(start_server)
asyncio.get_event_loop().run_forever()
and the client looks like this:
<!DOCTYPE html>
<html lang="en"><head>
<meta charset="UTF-8">
<title>Chat</title>
</head>
<body style="margin:0">
<script type="text/javascript">
var ws = new WebSocket("ws://127.0.0.1:6969/");
var messages = document.getElementById('messages');
ws.onmessage = function (event) {
var messages = document.getElementById('messages');
var message = document.createElement('li');
var content = document.createTextNode(event.data);
message.appendChild(content);
messages.appendChild(message);
};
</script>
Messages:
<ul id="messages"><li>Hello!</li></ul>
</body></html>
So the issue is that the client above works fine, until I run the server on my Ubuntu machine (and I've made sure to forward port 6969 to that machine) and try to connect over the internet. Hostname resolution is working fine, because I can ssh in to start the server, but trying to connect to the websocket always shows me the error message:
Firefox can’t establish a connection to the server at ws://<remote server url>:6969/.
or similiar for other browsers. Also, in case anyone was wondering, the logger isn't outputting anything useful (since the connection is failing the server isn't doing anything).
I'm just trying to get a very basic websocket connection over internet. The code seems fine - because it works when connecting to localhost - but for some reason fails when I try to use it over the internet. I'm using the websockets library, and my server looks like this:
#!/usr/bin/env python3
import asyncio
import websockets
from logging import getLogger, INFO, StreamHandler
logger = getLogger('websockets')
logger.setLevel(INFO)
logger.addHandler(StreamHandler())
clients = set()
async def handler(websocket, path):
global clients
clients.add(websocket)
try:
await asyncio.wait([ws.send("Hello!") for ws in clients])
await asyncio.sleep(10)
finally:
clients.remove(websocket)
start_server = websockets.serve(handler, host='127.0.0.1', port=6969)
asyncio.get_event_loop().run_until_plete(start_server)
asyncio.get_event_loop().run_forever()
and the client looks like this:
<!DOCTYPE html>
<html lang="en"><head>
<meta charset="UTF-8">
<title>Chat</title>
</head>
<body style="margin:0">
<script type="text/javascript">
var ws = new WebSocket("ws://127.0.0.1:6969/");
var messages = document.getElementById('messages');
ws.onmessage = function (event) {
var messages = document.getElementById('messages');
var message = document.createElement('li');
var content = document.createTextNode(event.data);
message.appendChild(content);
messages.appendChild(message);
};
</script>
Messages:
<ul id="messages"><li>Hello!</li></ul>
</body></html>
So the issue is that the client above works fine, until I run the server on my Ubuntu machine (and I've made sure to forward port 6969 to that machine) and try to connect over the internet. Hostname resolution is working fine, because I can ssh in to start the server, but trying to connect to the websocket always shows me the error message:
Firefox can’t establish a connection to the server at ws://<remote server url>:6969/.
or similiar for other browsers. Also, in case anyone was wondering, the logger isn't outputting anything useful (since the connection is failing the server isn't doing anything).
Share Improve this question edited Aug 29, 2017 at 16:46 ocket8888 asked Aug 29, 2017 at 16:34 ocket8888ocket8888 1,1401 gold badge15 silver badges35 bronze badges 4-
on the server I don't change any code, the only difference is when it's running on the remote server I change the line
var ws = new Websocket("ws://127.0.0.1:6969/");tovar ws = new Websocket("ws://<remote server url>:6969/");on the client. – ocket8888 Commented Aug 29, 2017 at 16:43 -
the
telnetmand properly resolves the IP address and attempts to connect but then says "connection refused". Also, if you could edit your ment to remove the url I'd appreciate it; I'm not ready for everyone to pentest me just yet :P (I'll edit it out of the question too - whoops) – ocket8888 Commented Aug 29, 2017 at 16:45 -
Change your
websockets.serve()line to this:websockets.serve(handler, port=6969). That should work equally well in either environment. – Robᵩ Commented Aug 29, 2017 at 16:47 -
@Robᵩ I changed it to
websockets.serve(handler, host="", port=6969)and now I can connect. If you wanna write an answer, I'd be happy to accept it, and I'd also appreciate an explanation of why what I did won't work. – ocket8888 Commented Aug 29, 2017 at 16:48
1 Answer
Reset to default 14Your line:
websockets.serve(handler, host='127.0.0.1', port=6969)
provides a specific address on which the websockets server listens. Your server will only listen on that address; any requests to any other address will never be seen.
From https://docs.python/3/library/asyncio-eventloop.html#asyncio.AbstractEventLoop.create_server :
The
hostparameter can be a string, in that case the TCP server is bound tohostandport. The host parameter can also be a sequence of strings and in that case the TCP server is bound to all hosts of the sequence. Ifhostis an empty string orNone, all interfaces are assumed and a list of multiple sockets will be returned (most likely one for IPv4 and another one for IPv6).
You have bound your webserver to 127.0.0.1, which is a special address that only ever refers to the local machine. This address is also known as localhost. No other machine can ever connect to your localhost.
The solution is to provide an empty string or None (the default value). In this case, your web server will listen for requests sent to any address.
websockets.serve(handler, port=6969)