使用ftplib连接到安全的ftp服务器（EOF发生违反协议）

Question

我在这个简单的连接/列表示例中出错了什么？ （我使用python 3.3）

import ftplib


ftp = ftplib.FTP_TLS()
ftp.connect('localhost', 221, 20)
ftp.login()
ftp.prot_p()
ftp.retrlines('LIST')

来源：https://docs.python.org/2/library/ftplib.html#ftplib.FTP_TLS

错误输出：

Traceback (most recent call last):
  File "C:/projects/nipples/ftps_client.py", line 10, in <module>
    ftp.login()
  File "C:\Python33\lib\ftplib.py", line 703, in login
    self.auth()
  File "C:\Python33\lib\ftplib.py", line 719, in auth
    ssl_version=self.ssl_version)
  File "C:\Python33\lib\ssl.py", line 630, in wrap_socket
    ciphers=ciphers)
  File "C:\Python33\lib\ssl.py", line 350, in __init__
    raise x
  File "C:\Python33\lib\ssl.py", line 346, in __init__
    self.do_handshake()
  File "C:\Python33\lib\ssl.py", line 553, in do_handshake
    self._sslobj.do_handshake()
ssl.SSLEOFError: EOF occurred in violation of protocol (_ssl.c:548)

提前致谢。