import socket, traceback
host = '' # Bind to all interfaces 
port = 51500
# Step1: 创建socket对象
s = socket.socket(socket.AF_INET, socket.SOCK_DGRAM)
# Step2: 设置socket选项(可选)
s.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1)
# Step3: 绑定到某一个端口
s.bind((host, port))
# Step4: 监听该端口上的连接
while 1:
  try:
    message, address = s.recvfrom(8192)
    print "Got data from ", address
    s.sendto("Data is received succeefully.", address)
  except (KeyboardInterrupt, SystemExit):
    print "raise"
    raise
  except :
    print "traceback"
    traceback.print_exc()

import socket, sys
# Step1: 输入host和port信息
host = raw_input('please input host name: ')
textport = raw_input('please input textport: ')
# Step2: 创建socket对象
s = socket.socket(socket.AF_INET, socket.SOCK_DGRAM)
try:
  port = int(textport)
except ValueError:
  port = socket.getservbyname(textport, 'udp')
# Step3: 打开socket连接  
s.connect((host, port))
# Step4: 发送数据
print "Enter data to transmit: "
data = sys.stdin.readline().strip()
s.sendall(data)
# Step5: 接收服务器发过来的数据
print "Looking for replies; press Ctrl-C or Ctrl-Break to stop"
while 1:
  buf = s.recv(2048)
  if not len(buf):
    break
  sys.stdout.write(buf)