Python FTPS upload error: 425 Unable to build data connection: Operation not permitted

Question

I'm trying to use ftps to send a file to a FTP server. Login and changing directory work:

import ftplib
ftps = ftplib.FTP_TLS('host','user','pwd')
ftps.set_pasv(True)
ftps.prot_p()
ftps.cwd('/target_directory')

however when I try to upload my file:

file = open(file, 'rb')
send_cmd = 'STOR file_name.txt'
ftps.storbinary(send_cmd, file)
file.close()
ftps.quit()

I get the following error:

File "/script/location/script.py", line 161, in <module>
ftps.storbinary(send_cmd,file)
File "/System/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/ftplib.py", line 772, in storbinary
return self.voidresp()
File "/System/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/ftplib.py", line 229, in voidresp
resp = self.getresp()
File "/System/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/ftplib.py", line 222, in getresp
raise error_temp, resp
ftplib.error_temp: 425 Unable to build data connection: Operation not permitted

I've read that the 425 response code is often a result of being in active mode, which is why I included ftps.set_pasv(True) (although this is True by default).

I've also tried just listing the directory contents using ftps.retrlines('LIST') but get essentially the same error. I'm using Python 2.7.10. Any help would be greatly appreciated.

Answer 1

This is a reported bug in python: https://bugs.python.org/issue19500

You can apply the patch in a new class

class Explicit_FTP_TLS(ftplib.FTP_TLS):
    """Explicit FTPS, with shared TLS session"""
    def ntransfercmd(self, cmd, rest=None):
        conn, size = ftplib.FTP.ntransfercmd(self, cmd, rest)
        if self._prot_p:
            conn = self.context.wrap_socket(conn,
                                            server_hostname=self.host,
                                            session=self.sock.session)
        return conn, size