"No hostkey for host ***** found" when connecting to SFTP server with pysftp using private key

Question

So I am having many issues connecting to a remote server via SFTP. I have tried the normal way like below.

sftp = pysftp.Connection(host='Host',username='username',password='passwd',private_key=".ppk")

Which did not work. I got the following error:

SSHException: No hostkey for host ***** found.

I then tried the following:

cnopts = pysftp.CnOpts()
cnopts.hostkeys = None
s = pysftp.Connection(host='host', username='user', password='password', cnopts=cnopts)

Which also did not work. I got the following error:

BadAuthenticationType: ('Bad authentication type', ['publickey']) (allowed_types=['publickey'])

Also when I run the following:

client = paramiko.SSHClient()
client.set_missing_host_key_policy(paramiko.AutoAddPolicy())
client.connect("host",username = "username",password = "password")
ssh_session = client.get_transport().open_session()

I get the same error:

BadAuthenticationType: ('Bad authentication type', ['publickey']) (allowed_types=['publickey'])

Answer 1

Your are confusing a private key used for authentication and a host key used to verify an identify of a server. Both need to be taken care of, while all your code attempts take care of one of them only. See my article on SSH key pairs to understand the difference between the two kinds of keys involved in SSH.

So this should "work":

# Accept any host key (still wrong see below)
cnopts = pysftp.CnOpts()
cnopts.hostkeys = None
# And authenticate with a private key
sftp = pysftp.Connection(
    host='Host', username='user', password='passwd', private_key=".ppk",
    cnopts=cnopts)

But this code will actually blindly accept any host key (cnopts.hostkeys = None), what is a security flaw. For a correct approach, see Verify host key with pysftp.

Answer 2

It looks like the host you are connecting is not available. This usually happens when the host-name is not accessible because of firewall rules (or typo on host). I'd recommend first checking if you can sftp from the (unix) terminal

> sftp username@host

If you get prompted for password or get logged in, you are able to connect to that host from that machine

If not try checking if that host is available using netcat on port 22, you'd get timeout or broken pipe if host is not available

>nc -v host 22

I recommend debugging the pysftp or paramiko packages only after that.

Also, if you are authenticating using a private key, you do not need to use the password.