python检测远程udp端口是否打开

import socket  import threading  import time  import struct  import Queue     queue = Queue.Queue()     def udp_sender(ip,port):      try:          ADDR = (ip,port)          sock_udp = socket.socket(socket.AF_INET,socket.SOCK_DGRAM)          sock_udp.sendto("abcd...",ADDR)          sock_udp.close()      except:          pass     def icmp_receiver(ip,port):      icmp = socket.getprotobyname("icmp")      try:          sock_icmp = socket.socket(socket.AF_INET, socket.SOCK_RAW, icmp)      except socket.error, (errno, msg):          if errno == 1:              # Operation not permitted              msg = msg + (                  " - Note that ICMP messages can only be sent from processes"                  " running as root."              )              raise socket.error(msg)          raise # raise the original error      sock_icmp.settimeout(3)      try:          recPacket,addr = sock_icmp.recvfrom(64)      except:          queue.put(True)          return      icmpHeader = recPacket[20:28]      icmpPort = int(recPacket.encode('hex')[100:104],16)      head_type, code, checksum, packetID, sequence = struct.unpack(              "bbHHh", icmpHeader      )      sock_icmp.close()      if code == 3 and icmpPort == port and addr[0] == ip:          queue.put(False)      return     def checker_udp(ip,port):         thread_udp = threading.Thread(target=udp_sender,args=(ip,port))      thread_icmp = threading.Thread(target=icmp_receiver,args=(ip,port))         thread_udp.daemon= True      thread_icmp.daemon = True         thread_icmp.start()      time.sleep(0.1)      thread_udp.start()         thread_icmp.join()      thread_udp.join()      return queue.get(False)     if __name__ == '__main__':      import sys      print checker_udp(sys.argv[1],int(sys.argv[2]))