crappy insecure python chat server

simplechat.py

import threading
from multiprocessing.connection import Listener
from multiprocessing.connection import Client
from array import array


def listen():
    address =  ('', 50000)
    listener = Listener(address)
    conn = listener.accept()

    while True:
        print conn.recv_bytes()


try:
    t = threading.Thread(target=listen)
    t.start()

    cmd = "default"

    print "username: ",
    username = raw_input()
    print "host: ",
    host = raw_input()
    print "port: ",
    port = raw_input()

    address = (host, int(port))
    client = Client(address)

    while cmd != '/end':
        cmd = raw_input()
        client.send_bytes(username + ': ' + cmd)

except KeyboardInterrupt:
    print "Listener exited."
    exit()