Python paramiko

last modified January 29, 2024

In this article we cover the Python paramiko module, which is used to work with the SSH protocol.

SSH is a network communication protocol that enables two computers to communicate and share data securely. The term SSH is used for the network protocol as well as for the to the suite of utilities that implement that protocol.

SSH tools are used by administrators for secure management of remote computers.

An SSH server, by default, listens on the TCP port 22.

OpenSSH

OpenSSH is a popular, open-source implementation of the SSH protocol.

OpenSSH provides the following tools:

ssh - client used to connect to a remote host
sshd - server on a remote host which enables a remote connection
ssh-keygen - generates, manages and converts authentication keys for SSH
ssh-agent - stores private keys used for public key authentication
ssh-add - adds private keys to the list allowed by the server
ssh-keyscan - helps collecting the public SSH host keys from hosts
sftp - service which provides an SFTP protocol over SSH
scp - client which copies files between hosts on a network

Paramiko

Paramiko is a Python implementation of the SSHv2 protocol. It provides both client and server functionality. It is a base library for the popular Fabric tool.

$ pip install paramiko

Paramiko is a third-party tool; it can be installed with the pip tool.

Python paramiko commad execution

In the first example, we execute a command on a remote host.

exec_cmd.py

#!/usr/bin/python

import paramiko

hostname = 'example.com'
port = 22

username = 'user7'
password = 'passwd'

cmd = 'uname'

with paramiko.SSHClient() as client:

    client.load_system_host_keys()
    client.connect(hostname, port, username, password)

    (stdin, stdout, stderr) = client.exec_command(cmd)

    output = stdout.read()
    print(str(output, 'utf8'))

In the program, we execute the uname command, which returns the name of the OS.

import paramiko

First, we import the paramiko module.

hostname = 'example.com'
port = 22

We provide the remote host name and port.

username = 'user7'
password = 'passwd'

We provide the username and password.

cmd = 'uname'

This is the command to be executed.

with paramiko.SSHClient() as client:

An SSH client is created.

client.load_system_host_keys()

We load the system host keys with load_system_host_keys.

client.connect(hostname, port, username, password)

We connect to the remote host with connect. We pass the hostname, port, username, and passowrd to the function.

(stdin, stdout, stderr) = client.exec_command(cmd)

The command is executed with exec_command function.

output = stdout.read()
print(str(output, 'utf8'))

Finally, we read and print the output from the remote host.

$ ./exec_cmd.py
Linux

In the second example, we list the contents of the current working directory.

list_dir.py

#!/usr/bin/python

import paramiko

hostname = 'example.com'
port = 22

username = 'user7'
password = 'passwd'

cmd = 'ls -l'

with paramiko.SSHClient() as client:

    client.load_system_host_keys()
    client.connect(hostname, port, username, password)

    (stdin, stdout, stderr) = client.exec_command(cmd)

    output = stdout.readlines()

    for line in output:
        print(line.rstrip())

To list the contents of a directory, we use the ls -l command.

output = stdout.readlines()

for line in output:
    print(line.rstrip())

We read the output into a list of lines with readlines. We go through the list and print each line.

Python paramiko download file

In the following example, we download a file over SSH.

download.py

#!/usr/bin/python

import paramiko

hostname = 'example.com'
port = 22

username = 'user7'
password = 'passwd'

remote_path = f'/home/{username}/data.txt'
output_file = 'data.txt'

with paramiko.SSHClient() as client:
    
    client.load_system_host_keys()
    client.connect(hostname, port, username, password)

    sftp_client = client.open_sftp()
    sftp_client.get(remote_path, output_file)

The example downloads the data.txt file which is located in the user's home directory.

sftp_client = client.open_sftp()

The SFTP client is created with open_sftp function.

sftp_client.get(remote_path, output_file)

We download the file with get function.

Python paramiko SFTP list directory

The next example lists the contents of a directory using SFTP.

list_dir.py

#!/usr/bin/python

import paramiko

hostname = 'example.com'
port = 22

username = 'user7'
password = 'passwd'

with paramiko.SSHClient() as client:
    
    client.load_system_host_keys()
    client.connect(hostname, port, username, password)

    sftp_client = client.open_sftp()
    sftp_client.chdir('tmp')
    contents = sftp_client.listdir()

    for line in contents:
        print(line)

We change to the destination directory with chdir and list the contents with listdir.

$ ./list_dir.py 
memo.txt
todo2.txt
notes.txt
test.py
pycp.py
todo.txt
docs

Source

Python paramiko documentation

In this article we have worked with SSH in Python utilizing the paramiko module.

Author

My name is Jan Bodnar and I am a passionate programmer with many years of programming experience. I have been writing programming articles since 2007. So far, I have written over 1400 articles and 8 e-books. I have over eight years of experience in teaching programming.

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