Failed to load HostKeys from directory - pysftp

Question

I'm trying to connect with an SFTP through an RSA Key pair that I generated. The server already added the public key to the server and I can access it using Filezilla. I'm following this post Verify host key with pysftp

However, I'm still getting the same error

C:\Users\John.Doe\Anaconda3\envs\EC_automation\lib\site-packages\pysftp\__init__.py:61: UserWarning: Failed to load HostKeys from C:\Users\John.Doe\.ssh\known_hosts.  You will need to explicitly load HostKeys (cnopts.hostkeys.load(filename)) or disableHostKey checking (cnopts.hostkeys = None).
  warnings.warn(wmsg, UserWarning)
Exception ignored in: <function Connection.__del__ at 0x00000256882C5C10>
Traceback (most recent call last):
  File "C:\Users\John.Doe\Anaconda3\envs\EC_automation\lib\site-packages\pysftp\__init__.py", line 1013, in __del__
    self.close()
  File "C:\Users\John.Doe\Anaconda3\envs\EC_automation\lib\site-packages\pysftp\__init__.py", line 784, in close
    if self._sftp_live:
AttributeError: 'Connection' object has no attribute '_sftp_live'

I'm using an anaconda virtual env under Python 3 under windows server 2016. This is my code

logging.info('Establishing connection with SFTP hosted in {}'.format(secrets.FTP_SERVER))
priv_key_path = os.path.join(os.path.dirname(os.path.abspath(__file__)), 'SSH keys', 'PrivateKeyDev.ppk')
logging.info('Key-based authentication. Keys in {}'.format(priv_key_path))

logging.debug('Adding keys to connection through cnopts')
cnopts = pysftp.CnOpts()
cnopts.hostkeys.add(secrets.FTP_SERVER, 'ssh-rsa', priv_key_path)

try:
    pysftp.Connection(secrets.FTP_SERVER, username=secrets.FTP_USER, cnopts=cnopts, private_key=priv_key_path, private_key_pass=secrets.KEY_PASS)
    logging.info('Connection with FTP server established')
except:
    logging.error('Unable to connect with {}'.format(secrets.FTP_SERVER))
    sys.exit()

I don't understand what's wrong with my approach. I can see the host in hostkeys

EDIT

setting cnopts.hostkeys = None and changing the format of the key to PEM resolves the issue, now the question is, how bad is to do this in production if this is using an internal network?

2nd EDIT

Thanks to the comments I realized I had a problem with the key I'm tryingg to add to the Host keys that contain public keys by definition. so I tried to add the public key instead of the private but didn't work either. Same error.

cnopts.hostkeys.add(secrets.FTP_SERVER, 'ssh-rsa', pub_key_path)

Martin Prikryl · Answer 1 · 2020-09-29T07:45:03.453

You are mixing two unrelated problems/keys. See Understanding SSH key pairs.

You are adding your user private key to the list of host public keys (aka hostkeys):

cnopts.hostkeys.add(secrets.FTP_SERVER, 'ssh-rsa', priv_key_path)

So 1) "setting cnopts.hostkeys = None" and 2) "changing the format of the key to PEM" solve two different problems. 1) solves (or actually avoids at the cost of security) the host key problem. 2) solves the authentication problem (user private key).

To actually solve the 1), go again through my answer to the question you know: Verify host key with pysftp – If it does not help, please ask new more specific question.

Failed to load HostKeys from directory - pysftp

1 Answers1