Python udp broadcast client server example.

README.md

Python udp broadcast client-server example

⚠️ ❗ ATTENTION ❗ ⚠️

This gist is deprecated and will not be edited in the future. Consider visit ninedraft/python-udp repo. It will not be deleted, however.

⚠️ ❗ ATTENTION ❗ ⚠️

Works for python 3.7 and 2.7 for Mac OS and Linux(kernel>=3.9) hosts. If you'ra using linux(kernel<3.9), then use socket.O_REUSEADDR instead of socket.SO_REUSEPORT to share (host, port) between multiple clients and servers.

Tricks and traps:

• Socket portability issues: How do SO_REUSEADDR and SO_REUSEPORT differ?;
• Awesome "Socket Programming HOWTO";

client.py

import socket

client = socket.socket(socket.AF_INET, socket.SOCK_DGRAM, socket.IPPROTO_UDP) # UDP

# Enable port reusage so we will be able to run multiple clients and servers on single (host, port). 
# Do not use socket.SO_REUSEADDR except you using linux(kernel<3.9): goto https://stackoverflow.com/questions/14388706/how-do-so-reuseaddr-and-so-reuseport-differ for more information.
# For linux hosts all sockets that want to share the same address and port combination must belong to processes that share the same effective user ID!
# So, on linux(kernel>=3.9) you have to run multiple servers and clients under one user to share the same (host, port).
# Thanks to @stevenreddie
client.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEPORT, 1)

# Enable broadcasting mode
client.setsockopt(socket.SOL_SOCKET, socket.SO_BROADCAST, 1)

client.bind(("", 37020))
while True:
    # Thanks @seym45 for a fix
    data, addr = client.recvfrom(1024)
    print("received message: %s"%data)

server.py

import socket
import time

server = socket.socket(socket.AF_INET, socket.SOCK_DGRAM, socket.IPPROTO_UDP)

# Enable port reusage so we will be able to run multiple clients and servers on single (host, port). 
# Do not use socket.SO_REUSEADDR except you using linux(kernel<3.9): goto https://stackoverflow.com/questions/14388706/how-do-so-reuseaddr-and-so-reuseport-differ for more information.
# For linux hosts all sockets that want to share the same address and port combination must belong to processes that share the same effective user ID!
# So, on linux(kernel>=3.9) you have to run multiple servers and clients under one user to share the same (host, port).
# Thanks to @stevenreddie
server.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEPORT, 1)

# Enable broadcasting mode
server.setsockopt(socket.SOL_SOCKET, socket.SO_BROADCAST, 1)

# Set a timeout so the socket does not block
# indefinitely when trying to receive data.
server.settimeout(0.2)
message = b"your very important message"
while True:
    server.sendto(message, ('<broadcast>', 37020))
    print("message sent!")
    time.sleep(1)

@bpsib @tianxie1989 I've fixed the broadcast host.
Try this for now please
https://github.com/ninedraft/python-udp

with your code how can I print IP Address Of Clients connected to SERVER,please help

with your code how can I print IP Address Of Clients connected to SERVER,please help

There is no such thing as connection in UDP, and server doesn't see any clients. It basically throws packets in the network and receives no answers.

https://www.youtube.com/watch?v=FfvUxw8DHb0

I tried with windows powershell, the client.py just blinks into oblivion and no message is received. Also I have a problem with breaking the function with CTRL+C since everything just freezes. Any tips to solve this?

@UgraNarasimha I'll try to reproduce it
Please, add an issue here https://github.com/ninedraft/python-udp

How I do it not in local network?
I'm trying do this:
client.bind(("broadcast_station_ip", 37020))
And I'm getting this:
Traceback (most recent call last): File "client.py", line 15, in <module> client.bind(("broadcast_station_ip", 37020)) File "/System/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/socket.py", line 228, in meth return getattr(self._sock,name)(*args) socket.error: [Errno 49] Can't assign requested address
For client.py I'm using macOS Big Sur 11.2.3 and for server.py I'm using Ubuntu 20.10.
It's work fine when:
client.bind(("", 37020))
and computers placed in local network.
If you have some idea or tips for solve this, please help me :)

Thank you for offer the code. I was runing the server and client codes on a group of remote machines. I wrote a powershell script to SSH into the server and client machines to start the python codes.
It seems the python codes freezes/hang the SSH every time. May I ask what is causing that and if there is a way around it? Thanks!