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#Python's UDP

User Datagram Protocol (UDP) is a connectionless, unreliable transport layer protocol, alongside TCP, and is one of the most common protocols on the Internet.

UDP programs do not have connections; they simply bind to their own address and send/receive data. The following example creates two sockets and sends data from one to the other.

import socket # Create UDP sockets sock1 = socket.socket(socket.AF_INET, socket.SOCK_DGRAM) sock2 = socket.socket(socket.AF_INET, socket.SOCK_DGRAM) # Bind own addresses sock1.bind(('0.0.0.0', 4000)) sock2.bind(('0.0.0.0', 4001)) # sock1 sends data to localhost:4001, which is sock2 sock1.sendto('hello\n'.encode(), ('localhost', 4001)) # sock2 receives data data, addr = sock2.recvfrom(1024) print(f'Received {data.decode()} from {addr}')
  • AF_INET indicates using IPv4 addresses,
  • SOCK_DGRAM indicates using UDP
  • The address argument is a tuple; the first element can be a domain name, hostname, or IP address, and the second element is the port number.

Created in 5/15/2025

Updated in 5/21/2025