# Python Paramiko Module

Paramiko is a Python implementation of the SSHv2 protocol, providing both client and server functionality. It allows you to connect to remote servers, execute commands, and transfer files via SFTP.

## Installation

```bash
pip install paramiko
```

## Importing the Module

```python
import paramiko
```

## SSH Client

To connect to a server and run commands, use the `SSHClient`.

### Connecting

```python
import paramiko

client = paramiko.SSHClient()

# Automatically add the server's host key (not recommended for production, but useful for testing)
client.set_missing_host_key_policy(paramiko.AutoAddPolicy())

# Connect to the server
client.connect('hostname', username='user', password='password')
```

### Executing Commands

`exec_command()` returns three file-like objects: standard input, standard output, and standard error.

```python
stdin, stdout, stderr = client.exec_command('ls -l')

# Read the output
print(stdout.read().decode())

# Check for errors
err = stderr.read().decode()
if err:
    print(f"Error: {err}")
```

### Closing Connection

```python
client.close()
```

## SFTP Client (File Transfer)

Paramiko supports SFTP (Secure File Transfer Protocol) for uploading and downloading files.

```python
# Open an SFTP session from an existing SSH client
sftp = client.open_sftp()

# Upload a file
sftp.put('local_file.txt', '/remote/path/remote_file.txt')

# Download a file
sftp.get('/remote/path/remote_file.txt', 'local_file.txt')

sftp.close()
```

## Key-Based Authentication

Instead of a password, you can use a private key file.

```python
k = paramiko.RSAKey.from_private_key_file("/path/to/private_key.pem")
client.connect('hostname', username='user', pkey=k)
```

[[programming/python/python]]