Paramiko's SSHClient with SFTP

Question

How I can make SFTP transport through SSHClient on the remote server? I have a local host and two remote hosts. Remote hosts are backup server and web server. I need to find on backup server necessary backup file and put it on web server over SFTP. How can I make Paramiko's SFTP transport work with Paramiko's SSHClient?

Answer 1

The accepted answer "works". But with its use of the low-level Transport class, it bypasses a host key verification, what is a security flaw, as it makes the code susceptible to Man-in-the-middle attacks.

Better is to use the right Paramiko SSH API, the SSHClient, which does verify the host key:

import paramiko
paramiko.util.log_to_file("paramiko.log")

ssh = paramiko.SSHClient()
ssh.connect(host, username='user', password='password')
# or 
# key = paramiko.RSAKey.from_private_key_file('id_rsa')
# ssh.connect(host, username='user', pkey=key)

sftp = ssh.open_sftp()

sftp.get(remotepath, localpath)
# or
sftp.put(localpath, remotepath)

---

For details about verifying the host key, see:
Paramiko "Unknown Server"

Answer 2

If you have a SSHClient, you can also use open_sftp():

import paramiko


# lets say you have SSH client...
client = paramiko.SSHClient()

sftp = client.open_sftp()

# then you can use upload & download as shown above
...

Answer 3

In addition to the first answer which is great but depends on username/password, the following shows how to use an ssh key:

from paramiko import Transport, SFTPClient, RSAKey
key = RSAKey(filename='path_to_my_rsakey')
con = Transport('remote_host_name_or_ip', 22)
con.connect(None,username='my_username', pkey=key)
sftp = SFTPClient.from_transport(con)
sftp.listdir(path='.')