Automate Cisco Devices Using Python Netmiko

Welcome to the exciting world of network automation using Python and Netmiko! Are you tired of repetitive network configuration tasks? Python, combined with the powerful Netmiko library, can revolutionize how you manage Cisco routers and switches. In this comprehensive guide, we'll dive into how you can use Python scripts to automate your network operations, making them more efficient, error-free, and scalable.

Why Use Python and Netmiko for Network Automation?

Before we jump into the coding part, let's understand why Python and Netmiko are preferred for automating Cisco devices. Python is known for its simplicity and readability, making it perfect for scripting and automation. Netmiko, developed by Kirk Byers, is an open-source Python library designed specifically for simplifying SSH connections to routers and switches. It supports a wide range of devices from Cisco and other vendors, making it an indispensable tool in any network administrator’s toolkit.

Using Python and Netmiko, you can perform tasks like configuration updates, routine backups, and multi-device command deployment without manual intervention. This not only saves time but also reduces the likelihood of human error, ensuring more reliable network operations.

Are you ready to streamline your network tasks? Let’s look at how you can start using Python with Netmiko to automate your Cisco devices effortlessly.

Setting Up Your Environment

First things first, setting up your Python environment with Netmiko is straightforward. You'll need to have Python installed on your computer along with pip, Python’s package installer. Here’s how you can get started:

• Install Python: Ensure Python (version 3.6 or higher) is installed. You can download it from the official Python website.
• Install Netmiko: Once Python and pip are set up, you can install Netmiko using pip. Simply run pip install netmiko in your command-line interface.
• Prepare Your Devices: Ensure that the Cisco devices you intend to manage are accessible via SSH, as Netmiko uses SSH for connections.

With your environment ready, you are now set to create some automation magic!

Basic Script to Connect to a Cisco Router

Let’s start with a basic script to connect to a Cisco router. This will be our foundation for more complex automation tasks. Here's a simple script to start:

import netmiko

connection = netmiko.ConnectHandler(
    device_type='cisco_ios',
    ip='your_router_ip',
    username='your_username',
    password='your_password'
)

print(connection.send_command('show version'))
connection.disconnect()

This script connects to your Cisco device, executes the show version command to retrieve hardware and software information, and then disconnects. It’s a simple yet powerful example of how you can use Python and Netmiko to communicate with network devices.

Interested in diving deeper into the capabilities of Netmiko? Check out this comprehensive guide on Netmiko's main concepts.

Expanding Your Scripts

Now that you’ve established a basic connection to a device, it’s time to expand your script to handle multiple devices and perform various tasks. What could we automate next? How about updating device configurations or performing routine backups? The possibilities are endless!

Automating Configuration Changes

One of the most common tasks in network management is updating device configurations. Using Python and Netmiko, you can automate this process across multiple devices, which is a significant time-saver. Here’s a step-by-step guide on how you can automate configuration changes:

1. Prepare Your Configuration File: Start by creating a text file that contains all the configuration commands you want to apply. Name it config_updates.txt. This file might include commands to change passwords, update access lists, or modify interface settings.
2. Write the Python Script: Below is a Python script that reads commands from your configuration file and applies them to the list of devices specified.

import netmiko

def update_device_config(device, config_file):
    try:
        connection = netmiko.ConnectHandler(**device)
        connection.enable()  # Entering privilege mode
        print(f"Connected to {device['ip']}")
        output = connection.send_config_from_file(config_file)
        print(output)  # Print the output from the configuration update
        connection.save_config()
        connection.disconnect()
        print(f"Configuration updated and saved for {device['ip']}")
    except netmiko.NetMikoTimeoutException:
        print("Failed to connect to device", device['ip'])
        
# List of devices to be updated
devices = [
    {'device_type': 'cisco_ios', 'ip': '192.168.1.1', 'username': 'admin', 'password': 'admin123'},
    {'device_type': 'cisco_ios', 'ip': '192.168.1.2', 'username': 'admin', 'password': 'admin123'},
    # add more devices if necessary
]

config_file = "config_updates.txt"

for device in devices:
    update_device_config(device, config_file)

This script demonstrates how you can loop through a list of devices, apply configuration updates from a file, and save these configurations. This approach is highly scalable, reducing the risk of errors that often occur with manual configurations.

Performing Routine Backups

Another essential task for network administrators is performing routine backups of device configurations. This ensures that you have recoverable data in the event of device failure or other issues. Here’s how to automate backups using Python and Netmiko:

import os
import datetime
import netmiko

backup_folder = 'config_backups'
os.makedirs(backup_folder, exist_ok=True)

def backup_config(device):
    connection = netmiko.ConnectHandler(**device)
    connection.enable()
    config_data = connection.send_command('show running-config')
    today = datetime.datetime.now().strftime('%Y-%m-%d')
    filename = f"{backup_folder}/config_{device['ip']}_{today}.txt"
    with open(filename, 'w') as file:
        file.write(config_data)
    print(f"Backup of {device['ip']} completed successfully.")
    connection.disconnect()

# List of devices to backup
devices = [
    {'device_type': 'cisco_ios', 'ip': '192.168.1.1', 'username': 'admin', 'password': 'admin123'},
    {'device_type': 'cisco_ios', 'ip': '192.168.1.2', 'username': 'admin', 'password': 'admin123'},
    # add more devices if necessary
]

for device in devices:
    backup_config(device)

This script not only automates the data retrieval process but also organizes it by date, making it much easier to manage backups over time. Automating these backups can significantly reduce the workload on network teams and help in maintaining consistent data integrity and availability.

Conclusion

By leveraging Python and the Netmiko library, network administrators can automate a wide array of tasks that typically consume a considerable amount of time and are prone to manual errors. From connecting to a Cisco router, applying bulk configuration changes, to backing up configurations, automation not only increases efficiency but also enhances the consistency and reliability of network operations.

Automating your Cisco device operations with Python and Netmiko is not only about simplifying repetitive tasks; it's about transforming the way networks are managed and maintained. As networks grow in complexity and size, the ability to swiftly and reliably push changes or perform routine backups becomes invaluable. We encourage you to expand on these scripts, tailor them to your specific needs, and explore further possibilities to maximize the efficiency of your network management.

Embrace network automation today and see how it can revolutionize your workflow, reduce operational costs, and improve the overall reliability of your network. Happy automating!