python - ftplib - 504 安全机制 'TLS' 未实现

Question

我正在尝试使用 ftplib 连接到安全 FTP，但由于某种原因它不起作用(尝试连接到 www.sharefile.com ftp。它说要使用这个地址:公司.sharefileftp.com)

我正在尝试这种方法(FTPES - FTP over explicit TLS/SSL in Python):

from ftplib import FTP_TLS
ftps = FTP_TLS('company.sharefileftp.com')
ftps.login('user', 'pass')           # login anonymously before securing control channel
ftps.prot_p()          # switch to secure data connection.. IMPORTANT! Otherwise, only the user and password is encrypted and not all the file data.
ftps.retrlines('LIST')

filename = 'remote_filename.bin'
print 'Opening local file ' + filename
myfile = open(filename, 'wb')

ftps.retrbinary('RETR %s' % filename, myfile.write)

ftps.close()

但它给了我这个错误(调用此行 ftps.login('testuser', 'testpass') 时):

error_perm                                Traceback (most recent call last)
<ipython-input-17-bfe01179f1c2> in <module>()
----> ftps.login('user', 'pass')

/usr/lib/python2.7/ftplib.pyc in login(self, user, passwd, acct, secure)
    650         def login(self, user='', passwd='', acct='', secure=True):
    651             if secure and not isinstance(self.sock, ssl.SSLSocket):
--> 652                 self.auth()
    653             return FTP.login(self, user, passwd, acct)
    654 

/usr/lib/python2.7/ftplib.pyc in auth(self)
    658                 raise ValueError("Already using TLS")
    659             if self.ssl_version == ssl.PROTOCOL_TLSv1:
--> 660                 resp = self.voidcmd('AUTH TLS')
    661             else:
    662                 resp = self.voidcmd('AUTH SSL')

/usr/lib/python2.7/ftplib.pyc in voidcmd(self, cmd)
    252         """Send a command and expect a response beginning with '2'."""
    253         self.putcmd(cmd)
--> 254         return self.voidresp()
    255 
    256     def sendport(self, host, port):

/usr/lib/python2.7/ftplib.pyc in voidresp(self)
    227     def voidresp(self):
    228         """Expect a response beginning with '2'."""
--> 229         resp = self.getresp()
    230         if resp[:1] != '2':
    231             raise error_reply, resp

/usr/lib/python2.7/ftplib.pyc in getresp(self)
    222             raise error_temp, resp
    223         if c == '5':
--> 224             raise error_perm, resp
    225         raise error_proto, resp
    226 

error_perm: 504 Security mechanism 'TLS' not implemented.

P.S. 但我可以使用 FTP(不安全的)连接:

>>> from ftplib import FTP
>>> ftp = FTP('company.sharefileftp.com')     # connect to host, default port
>>> ftp.login('user', 'pass')                     # user anonymous, passwd anonymous@

Answer 1

服务器根本不支持 TLS，旧的“AUTH SSL”和新的“AUTH TLS”都不支持。此问题与 python 无关，因为以下使用 telnet 进行的测试显示:

$telnet company.sharefileftp.com 21
Trying 54.194.108.219...
Connected to company.sharefileftp.com.
Escape character is '^]'.
220 ftp-eu-1.sharefileftp.com FTP Server Ready
AUTH TLS
504 Security mechanism 'TLS' not implemented.
AUTH SSL
504 Security mechanism 'SSL' not implemented.
QUIT
221-Sent: 142 bytes   Rcvd: 26 bytes   Time: 15s
221 ftp-eu-1.sharefileftp.com session ended.
Connection closed by foreign host.

但它确实支持(旧的且从未标准化的)隐式 TLS:

$ openssl s_client -connect company.sharefileftp.com:990
...
SSL-Session:
    Protocol  : TLSv1
   Cipher    : RC4-SHA
...
220 ftp-eu-1.sharefileftp.com FTP Server Ready (SSL)