import socket import sys sock = socket.socket(socket.AF_INET, socket.SOCK_DGRAM) addr = ('localhost', int(sys.argv[1])) print('listening on %s port %s' % addr, file=sys.stderr) sock.bind(addr) while True: buf, raddr = sock.recvfrom(4096) print(buf.decode("utf-8"), file=sys.stderr) if buf: sent = sock.sendto(b'this is the host!', raddr)