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?

Solution 1

paramiko.SFTPClient

Sample Usage:

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

# Open a transport
host,port = "example.com",22
transport = paramiko.Transport((host,port))

# Auth    
username,password = "bar","foo"
transport.connect(None,username,password)

# Go!    
sftp = paramiko.SFTPClient.from_transport(transport)

# Download
filepath = "/etc/passwd"
localpath = "/home/remotepasswd"
sftp.get(filepath,localpath)

# Upload
filepath = "/home/foo.jpg"
localpath = "/home/pony.jpg"
sftp.put(localpath,filepath)

# Close
if sftp: sftp.close()
if transport: transport.close()

Solution 2

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"

Solution 3

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
...

Solution 4

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='.')

View more solutions

Comments

[ayorgo]

Great answer. I'd add however that both Transport and SFTPClient implement the __enter__/__exit__ interface thus can be used within a context manager e.g. with Transport((host, port)) as transport:

[Martin Prikryl]

First, this is not a standalone answer, but mere comment to @leoluk's answer. Second, if you have SSHClient, you can simply do sftp = client.open_sftp().

[Saurabh Nemade]

This implementation works however it does not cleanup processes. sftp-server process is forked with it and if you run it multiple times you can see there are a lot of processes exists after the completion of code.

[Martin Prikryl]

While this works, 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. See my answer.