Python server programming: Using Paramiko to implement SSH remote operation

With the development of cloud computing and the Internet of Things, remote operation of servers has become more and more important. In Python, we can use the Paramiko module to easily implement SSH remote operations. In this article, we will introduce the basic usage of Paramiko and how to use Paramiko in Python to remotely manage servers.

What is Paramiko

Paramiko is a Python module for SSHv1 and SSHv2 that can be used to connect and control SSH clients and SSH servers. Using the Paramiko module, you can easily write Python scripts to remotely log in and operate the server.

Basic usage of Paramiko

The basic usage of Paramiko module is very simple. We can use Paramiko's SSHClient class to create an SSH client object and connect to the SSH server. Here is a basic example:

import paramiko

ssh = paramiko.SSHClient()
ssh.set_missing_host_key_policy(paramiko.AutoAddPolicy())
ssh.connect('hostname', username='username', password='password')

In this example, we first create an SSHClient object and use the set_missing_host_key_policy method to allow missing SSH keys to be added automatically. We then connect to the SSH server using the connect method, passing in the hostname, username, and password as parameters.

Now, we have successfully connected to the SSH server. Next, we can use the SSHClient object to execute remote commands, such as obtaining the server's operating system information:

stdin, stdout, stderr = ssh.exec_command('uname -a')
print(stdout.read())

In this example, we use the exec_command method to execute the uname -a command and obtain the output. We also used stdout.read() to read the output and print it.

In addition to executing remote commands, we can also use the SSHClient object to upload and download files. The following is an example of uploading files:

sftp = ssh.open_sftp()
local_file = '/path/to/local/file.txt'
remote_file = '/path/to/remote/file.txt'
sftp.put(local_file, remote_file)
sftp.close()

In this example, we first use the open_sftp method to open an SFTP session, and use the put method to upload local files to the remote server. We also used the sftp.close() method to close the SFTP session.

Use Paramiko to implement SSH remote operation

Now that we have understood the basic usage of Paramiko, next, we will use Paramiko to remotely operate the server. We will implement the following functionality:

• Connect to an SSH server and execute some basic commands
• Create and delete folders
• Upload and download files

First, we need to install the Paramiko module:

pip install paramiko

Next, we write a Python script. First, we import the necessary modules:

import os
import paramiko

Then, we define some constants, including the hostname, username, and password of the SSH server:

HOST = 'hostname'
USER = 'username'
PASSWORD = 'password'

Next, we can use paramiko.SSHClient Class to connect to an SSH server:

ssh = paramiko.SSHClient()
ssh.set_missing_host_key_policy(paramiko.AutoAddPolicy())
ssh.connect(HOST, username=USER, password=PASSWORD)

In this example, we use the set_missing_host_key_policy() method to automatically add missing SSH keys.

Next, we will define some functions to perform different tasks. The first is the function that executes the command:

def run_command(command):
    stdin, stdout, stderr = ssh.exec_command(command)
    output = stdout.read().decode('utf-8')
    return output

This function receives a command parameter, uses the exec_command method of the SSHClient object to execute the command, and returns the output as a string.

Next, we define a function to create a directory:

def create_directory(path):
    sftp = ssh.open_sftp()
    try:
        sftp.mkdir(path)
    except IOError:
        pass
    sftp.close()

This function receives a path parameter and creates a directory using an SFTP session.

We also define functions to upload and download files:

def upload_file(local_path, remote_path):
    sftp = ssh.open_sftp()
    sftp.put(local_path, remote_path)
    sftp.close()


def download_file(remote_path, local_path):
    sftp = ssh.open_sftp()
    sftp.get(remote_path, local_path)
    sftp.close()

These functions receive a local path and remote path (for uploading) or a remote path and local path (for downloading) respectively ), and use an SFTP session to upload or download the corresponding files.

Finally, we will define a main function to perform all tasks:

def main():
    # Run a command
    output = run_command('ls -la')
    print(output)

    # Create a directory
    create_directory('/home/username/new_folder')

    # Upload a file
    upload_file('/path/to/local/file.txt', '/home/username/new_folder/file.txt')

    # Download a file
    download_file('/home/username/new_folder/file.txt', '/path/to/local/file.txt')

    # Close the SSH connection
    ssh.close()

This main function performs the following tasks:

• Execute the ls -la command and print Output
• Created a new directory
• Uploaded a file
• Downloaded the same file
• Closed SSH connection

Now, we can run this script and view the output:

python ssh.py

The result should be something like the following:

total 20
drwxr-xr-x 1 username username 4096 Aug 15 02:24 .
drwxr-xr-x 1 username username 4096 Aug 15 02:20 ..
-rw------- 1 username username 1675 Aug 15 02:21 .bash_history
-rw-r--r-- 1 username username  220 Aug 15 02:20 .bash_logout
-rw-r--r-- 1 username username 3771 Aug 15 02:20 .bashrc
drwx------ 1 username username 4096 Aug 15 02:20 .cache
drwxr-xr-x 1 username username 4096 Aug 15 02:20 .config
drwx------ 1 username username 4096 Aug 15 02:20 .gnupg
-rw-r--r-- 1 username username  807 Aug 15 02:20 .profile
-rw-r--r-- 1 username username    0 Aug 15 02:21 test.txt

Summary

SSH remote can be easily achieved using the Paramiko module operate. In this article, we introduced the basic usage of Paramiko and demonstrated how to use Paramiko in Python to remotely manage servers. Whether in the field of cloud computing or the Internet of Things, Paramiko is a very useful tool that can help us automate server management.

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