I have a problem connecting via SSH to a WS-FTP server using Python3 ftplib for the client.
Here's a small example:
import ftplib
sess = ftplib.FTP_TLS()
sess.connect(<hostname>, 22)
This just hangs in sess.connect. Here's the traceback from connect():
Traceback (most recent call last):
File "o:/Thy.Python/logls.py", line 19, in <module>
logs = u.newSession()
File "/cygdrive/o/Thy.Python/logutils.py", line 41, in newSession
sess.connect(findsys(), 22)
File "/usr/lib/python3.6/ftplib.py", line 155, in connect
self.welcome = self.getresp()
File "/usr/lib/python3.6/ftplib.py", line 234, in getresp
resp = self.getmultiline()
File "/usr/lib/python3.6/ftplib.py", line 224, in getmultiline
nextline = self.getline()
File "/usr/lib/python3.6/ftplib.py", line 202, in getline
line = self.file.readline(self.maxline + 1)
File "/usr/lib/python3.6/socket.py", line 586, in readinto
return self._sock.recv_into(b)
Wireshark shows this:
2017-06-14 11:26:21.623858 <Client> <Server> TCP 66 57092 › 22 [SYN] Seq=0 Win=8192 Len=0 MSS=1460 WS=256 SACK_PERM=1
2017-06-14 11:26:21.625280 <Server> <Client> TCP 62 22 › 57092 [SYN, ACK] Seq=0 Ack=1 Win=4380 Len=0 MSS=1460 SACK_PERM=1
2017-06-14 11:26:21.625428 <Client> <Server> TCP 54 57092 › 22 [ACK] Seq=1 Ack=1 Win=64240 Len=0
2017-06-14 11:26:21.649362 <Server> <Client> SSH 78 Server: Protocol (SSH-2.0-WS_FTP-SSH_7.7)
2017-06-14 11:26:21.843439 <Client> <Server> TCP 54 57092 › 22 [ACK] Seq=1 Ack=25 Win=64216 Len=0
Two things stand out:
- ftplib() (or its subordinate libraries) doesn't appear to send an SSH Client: Protocol message
- After the server responds with its Server: Protocol message, ftplib just sends an ACK and doesn't initiate key exchange.
Can anyone suggest what's happening, and how to fix it? I'm afraid I'm on the cliff-edge of my competence here.
