关于FTP的 怎么运行就报错~~新手求问~~

>>>from ftplib import FTP
>>>f = FTP("ftp.)
报错
Traceback (most recent call last):
  File "<pyshell#1>", line 1, in <module>
    f = FTP('ftp.')
  File "C:\Python27\lib\ftplib.py", line 117, in __init__
    self.connect(host)
  File "C:\Python27\lib\ftplib.py", line 135, in connect
    self.welcome = self.getresp()
  File "C:\Python27\lib\ftplib.py", line 210, in getresp
    resp = self.getmultiline()
  File "C:\Python27\lib\ftplib.py", line 196, in getmultiline
    line = self.getline()
  File "C:\Python27\lib\ftplib.py", line 183, in getline
    line = self.file.readline()
  File "C:\Python27\lib\socket.py", line 447, in readline
    data = self._sock.recv(self._rbufsize)
error: [Errno 10054]


联网了~还是报错 就算换另一个 FTP的网址也是报同样的错  请问这是怎么回事嗯~~~~~~？？？？？不懂~~~