Not receiving data from Websockify

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I'm trying to use websockify 0.11.0 to take the data from an incoming websocket connection and forward that data to another server.

On one server (172.16.2.5) I have the following Python application that creates a WebSocket connection to the server running websockify and repeatedly sends a message:

from time import sleep

from websocket import create_connection

ws = create_connection("ws://172.16.2.6:80/")

while True:

    print("Sending...")

    ws.send("Hello world")

    print("Sent")

    sleep(5)

On the 172.16.2.6 server, websockify was started with the following command to forward messages to the 172.16.2.7 server:

./run -v 80 172.16.2.7:33333

On the 172.16.2.7 server, the following Python application is supposed to receive messages from websockify:

import socket, time

with socket.socket(socket.AF_INET, socket.SOCK_STREAM) as s:

    s.bind(('', 33333))

    s.listen()

    conn, addr = s.accept()

    with conn:

        print("Connected by", addr)

        while True:

            data = conn.recv(11)

            print("Received: %s" % data)

            time.sleep(5)

When I start the application on 172.16.2.5, it sends the messages with no errors, and prints out the following:

Sending... 

Sent

Sending...

Sent

Sending...

Sent

After the application on 172.16.2.5 has started, websockify immediately prints out the following:

172.16.2.5: new handler Process

172.16.2.5 - - [07/Jun/2024 15:40:36] "GET / HTTP/1.1" 101 -

172.16.2.5 - - [07/Jun/2024 15:40:36] 172.16.2.5: Plain non-SSL (ws://) WebSocket connection

172.16.2.5 - - [07/Jun/2024 15:40:36] connecting to: 172.16.2.7:33333

The application on 172.16.2.7 immediately prints out the following after the application on 172.16.2.5 has started:

Connected by ('172.16.2.6', 32906)

But there are a couple of problems. First, the application on 172.16.2.7 blocks on the call to conn.recv(11) forever until I stop the application on 172.16.2.5. Once the application on 172.16.2.5 is stopped, the application on 172.16.2.7 finally starts printing out the "Received:" messages every 5 seconds.

Second, the application on 172.16.2.7 does not receive any data from websockify. It just keeps printing out "Received: b''" (an empty byte string) every 5 seconds. I would expect it to print out "Received: Hello world" every 5 seconds.

Anyone know why websockify isn't sending the data from the 172.16.2.5 application to the 172.16.2.7 application?