Question

this is my first post on here so I’m happy to be a part of the community. I have a fairly mundane question to ask, but it’s been a fairly annoying problem so I’m hoping to find answers.

So I’m trying to use Python’s FTPLIB module to retrieve a binary file.

The code entered directly into the interpreter looked like this:

>>> from ftplib import FTP 

>>> ftp = FTP('xxx.xx.xx.x')  # IP of target device

>>> ftp.login()

>>> file = "foobar.xyz" # target file 

>>> ftp.retrbinary("RETR " + file, open('filez.txt', 'wb').write)

While certain functions are working (I can view all files on the device, get the welcome message from the FTP server application, and even rename files), when I try to execute the last command above, I get

    error_perm                                Traceback (most recent call last)

/Users/user_name/<ipython console> in <module>()

/opt/local/Library/Frameworks/Python.framework/Versions/2.6/lib/python2.6/ftplib.pyc in retrlines(self, cmd, callback)
    419         if callback is None: callback = print_line
    420         resp = self.sendcmd('TYPE A')
--> 421         conn = self.transfercmd(cmd)
    422         fp = conn.makefile('rb')
    423         while 1:

/opt/local/Library/Frameworks/Python.framework/Versions/2.6/lib/python2.6/ftplib.pyc in transfercmd(self, cmd, rest)
    358     def transfercmd(self, cmd, rest=None):
    359         """Like ntransfercmd() but returns only the socket."""
--> 360         return self.ntransfercmd(cmd, rest)[0]
    361 
    362     def login(self, user = '', passwd = '', acct = ''):

/opt/local/Library/Frameworks/Python.framework/Versions/2.6/lib/python2.6/ftplib.pyc in ntransfercmd(self, cmd, rest)
    327             if rest is not None:
    328                 self.sendcmd("REST %s" % rest)
--> 329             resp = self.sendcmd(cmd)
    330             # Some servers apparently send a 200 reply to

    331             # a LIST or STOR command, before the 150 reply


/opt/local/Library/Frameworks/Python.framework/Versions/2.6/lib/python2.6/ftplib.pyc in sendcmd(self, cmd)
    241         '''Send a command and return the response.'''
    242         self.putcmd(cmd)
--> 243         return self.getresp()
    244 
    245     def voidcmd(self, cmd):

/opt/local/Library/Frameworks/Python.framework/Versions/2.6/lib/python2.6/ftplib.pyc in getresp(self)
    216             raise error_temp, resp
    217         if c == '5':
--> 218             raise error_perm, resp
    219         raise error_proto, resp
    220 

error_perm: 502 Command not implemented.

I’ve looked through the ftplib source but my programming experience with these sorts of task is pretty limited, as I normally use Python for math and haven’t had to work with FTP before.

So, if anyone could give me some ideas on a solution, that would be a huge help. Alternatively, if you could suggest another solution path in a different language that would be equally helpful.

Answer 1

It looks like you are logging-in anonymously (no username/password specified in ftp.login()) thus you get permission error. Try logging-in with

ftp.login(user='foo', passwd='bar')

instead.

Edit: here is a short example of ftplib usage (simplistic, without error handling):

#!/usr/bin/env python

from ftplib import FTP

HOST   = "localhost"
UNAME  = "foo"
PASSWD = "bar"
DIR    = "pub"
FILE   = "test.test"

def download_cb(block):
    file.write(block)

ftp = FTP(HOST)
ftp.login(user=UNAME, passwd=PASSWD)
ftp.cwd(DIR)

file = open(FILE, "wb")
ftp.retrbinary("RETR " + FILE, download_cb)
file.close()
ftp.close()

_{Note: In case retrbinary doesn’t work, you can also try setting binary mode explicitly with ftp.sendcmd("TYPE I") before calling it. This is non-typical case, however may help with some exotic ftp servers.}