import pysftp as sftp
from base64 import decodebytes
import paramiko

keydata = b"""AAAAB3NzaC1yc2EAAAADAQABAAABAQC5EVdi40ppCS+ctFidNOUxKOkzZbKkHzWYMnM+q3qvqqiouNSWlpU/zNinxIh5mQPCZnzK67dhhJfIzIoRiZ4D9/geTEeWqOtf4LjDveGEx/WCU6sjL1IUQFFa   /1oI8SyfYKwzxLNcJ7nRBCpwrnDngLPuYEurDTdy5lx8MP6VLlLqm3nGN77YtB+vuQKBZ437uduVy6xH0abcuB6H3S26EfyQoWZBJng1jn/O2yXvNhtNpVMKueCuW4NXbJoqPAU9/U6F0YGH9w2qsXFXdfdBUljonEady0vnB2ieAnUe7q1QTJ6MX+UvrEyg/EK7xHNe4GgBWM5dfRXF56B2tbYn"""
key = paramiko.RSAKey(data=decodebytes(keydata))
cnopts = pysftp.CnOpts()
cnopts.hostkeys.add('s-936a09baf53d41da9.server.transfer.eu-central-1.amazonaws.com', 'ssh-rsa', key)
 
with pysftp.Connection('s-936a09baf53d41da9.server.transfer.eu-central-1.amazonaws.com', 'user', 'xxxx', cnopts=cnopts) as sftp:
    #with sftp.cd('/pmd-bisnode-dnb/test/'):           # temporarily chdir to allcode
         print(sftp.listdir())
         #sftp.get('Bayer_CMPELK_DEV_20210326045204_SEEDFILE_HEADER.json') 

Error:
---------------------------------------------------------------------------
SSHException                              Traceback (most recent call last)
<command-34066901391228> in <module>
      8 cnopts.hostkeys.add('s-936a09baf53d41da9.server.transfer.eu-central-1.amazonaws.com', 'ssh-rsa', key)
      9 
---> 10 with pysftp.Connection('s-936a09baf53d41da9.server.transfer.eu-central-1.amazonaws.com', 'user', 'xxx', cnopts=cnopts) as sftp:
     11     #with sftp.cd('/pmd-bisnode-dnb/test/'):           # temporarily chdir to allcode
     12          print(sftp.listdir())

/local_disk0/.ephemeral_nfs/envs/pythonEnv-02b3e90a-fb4b-4efb-9cfe-85dc962946d6/lib/python3.8/site-packages/pysftp/__init__.py in __init__(self, host, username, private_key, password, port, private_key_pass, ciphers, log, cnopts, default_path)
    138         # Begin the SSH transport.
    139         self._transport = None
--> 140         self._start_transport(host, port)
    141         self._transport.use_compression(self._cnopts.compression)
    142         self._set_authentication(password, private_key, private_key_pass)

/local_disk0/.ephemeral_nfs/envs/pythonEnv-02b3e90a-fb4b-4efb-9cfe-85dc962946d6/lib/python3.8/site-packages/pysftp/__init__.py in _start_transport(self, host, port)
    174         '''start the transport and set the ciphers if specified.'''
    175         try:
--> 176             self._transport = paramiko.Transport((host, port))
    177             # Set security ciphers if set
    178             if self._cnopts.ciphers is not None:

/local_disk0/.ephemeral_nfs/envs/pythonEnv-02b3e90a-fb4b-4efb-9cfe-85dc962946d6/lib/python3.8/site-packages/paramiko/transport.py in __init__(self, sock, default_window_size, default_max_packet_size, gss_kex, gss_deleg_creds, disabled_algorithms, server_sig_algs)
    439                         break
    440             else:
--> 441                 raise SSHException(
    442                     "Unable to connect to {}: {}".format(hostname, reason)
    443                 )

SSHException: Unable to connect to s-936a09baf53d41da9.server.transfer.eu-central-1.amazonaws.com: [Errno 111] Connection refused