Using Paramiko for SSH Automation in Python

Paramiko is a powerful Python library used for SSH (Secure Shell) automation. It allows you to automate remote server access, execute commands, transfer files, and manage SSH connections.

1. Installing Paramiko

Before using Paramiko, install it via pip:

pip install paramiko

2. Establishing an SSH Connection

To connect to a remote server using username & password:

import paramiko

host = "your.server.com"
port = 22
username = "your_username"
password = "your_password"

# Create SSH client
ssh = paramiko.SSHClient()
ssh.set_missing_host_key_policy(paramiko.AutoAddPolicy())  # Auto-accepts unknown hosts

# Connect to the server
ssh.connect(hostname=host, port=port, username=username, password=password)

# Run a command
stdin, stdout, stderr = ssh.exec_command("ls -l")
print(stdout.read().decode())  # Output the command result

# Close the connection
ssh.close()

✔ set_missing_host_key_policy(paramiko.AutoAddPolicy()) → Automatically accepts unknown SSH keys.
✔ exec_command("command") → Runs a shell command remotely.

3. Using SSH Key Authentication

For more security, use SSH keys instead of passwords:

private_key_path = "/path/to/private/key"

ssh = paramiko.SSHClient()
ssh.set_missing_host_key_policy(paramiko.AutoAddPolicy())

# Load private key
private_key = paramiko.RSAKey(filename=private_key_path)

# Connect using the private key
ssh.connect(hostname=host, port=port, username=username, pkey=private_key)

stdin, stdout, stderr = ssh.exec_command("whoami")
print(stdout.read().decode())

ssh.close()

✔ Uses RSA private key authentication instead of passwords.
✔ More secure and avoids storing plaintext passwords.

4. Transferring Files via SFTP

Paramiko supports SFTP (Secure File Transfer Protocol) to upload and download files.

📂 Uploading a File

sftp = ssh.open_sftp()
sftp.put("local_file.txt", "/remote/path/remote_file.txt")
sftp.close()
ssh.close()

✔ put(local, remote) → Uploads a local file to a remote server.

📂 Downloading a File

sftp = ssh.open_sftp()
sftp.get("/remote/path/remote_file.txt", "local_file.txt")
sftp.close()
ssh.close()

✔ get(remote, local) → Downloads a file from the remote server.

5. Automating Multiple Commands

Instead of opening multiple connections, use shell interaction:

shell = ssh.invoke_shell()
shell.send("cd /var/logs\n")
shell.send("ls -la\n")
shell.send("exit\n")
output = shell.recv(4096)
print(output.decode())
ssh.close()

✔ invoke_shell() → Opens an interactive SSH session.
✔ send("command\n") → Sends commands like a real SSH session.

6. Running Commands on Multiple Servers

Automate SSH tasks across multiple servers:

servers = [
    {"host": "server1.com", "user": "user1", "password": "pass1"},
    {"host": "server2.com", "user": "user2", "password": "pass2"},
]

for server in servers:
    ssh = paramiko.SSHClient()
    ssh.set_missing_host_key_policy(paramiko.AutoAddPolicy())
    ssh.connect(server["host"], username=server["user"], password=server["password"])

    stdin, stdout, stderr = ssh.exec_command("uptime")
    print(f"Server: {server['host']} - Uptime: {stdout.read().decode()}")

    ssh.close()

✔ Loops through multiple servers, executing the same command remotely.
✔ Useful for batch server automation.

7. Handling Errors Gracefully

Always handle exceptions to avoid script crashes:

try:
    ssh = paramiko.SSHClient()
    ssh.set_missing_host_key_policy(paramiko.AutoAddPolicy())
    ssh.connect(hostname="wrong_host", username="user", password="pass")
except paramiko.AuthenticationException:
    print("Authentication failed.")
except paramiko.SSHException as e:
    print(f"SSH error: {e}")
finally:
    ssh.close()

✔ Catches authentication and SSH errors.
✔ finally ensures proper cleanup.

8. Automating SSH Commands on a Schedule

Use cron jobs (Linux) or Task Scheduler (Windows) to run scripts at intervals.

Example: Automate server monitoring every hour:

import paramiko
import time

def monitor_server():
    ssh = paramiko.SSHClient()
    ssh.set_missing_host_key_policy(paramiko.AutoAddPolicy())
    ssh.connect(hostname="your.server.com", username="your_user", password="your_pass")

    stdin, stdout, stderr = ssh.exec_command("df -h")
    print(stdout.read().decode())

    ssh.close()

while True:
    monitor_server()
    time.sleep(3600)  # Run every 1 hour

✔ Checks disk space (df -h) every hour.
✔ Can be modified for CPU, memory, or log monitoring.

9. Deploying Paramiko Scripts on a Server

Upload your script to a Linux server.
Make it executable: chmod +x script.py
Run it in the background: bashCopyEditnohup python3 script.py &