Table of Contents
Introduction
In this tutorial, we will explore how to automate network configuration tasks using Python. As a sysadmin, managing and configuring network devices can often be time-consuming and error-prone. With Python, we can write scripts to automate these tasks, saving time and reducing human error.
By the end of this tutorial, you will learn how to use Python to interact with network devices, retrieve device information, and perform common configuration tasks.
Prerequisites
Before you begin this tutorial, you should have some basic knowledge of Python programming. Familiarity with networking concepts such as IP addresses, subnets, and device configuration will also be helpful.
Setup
To follow along with the examples in this tutorial, you will need the following:
- Python installed on your machine. You can download the latest version of Python from the official Python website: https://www.python.org/downloads/
- An SSH client (such as PuTTY) to connect to network devices remotely.
Automating Network Configuration using Python
Step 1: Installing the Required Libraries
To begin, we need to install the necessary Python libraries that will help us interact with network devices. Open a command prompt or terminal and run the following command:
python
pip install netmiko
This command will install the netmiko library, which provides a simple and consistent API for interacting with network devices.
Step 2: Connecting to a Network Device
Before we can start configuring a device, we need to establish a connection to it. We’ll use the ConnectHandler class from the netmiko library to establish an SSH connection.
```python
from netmiko import ConnectHandler
device = {
'device_type': 'cisco_ios',
'host': '192.168.0.1',
'username': 'admin',
'password': 'password',
}
connection = ConnectHandler(**device)
``` In this example, we define a dictionary with the device details, such as the device type (`cisco_ios`), IP address (`192.168.0.1`), username, and password. We then pass this dictionary to the `ConnectHandler` class to establish a connection.
Step 3: Retrieving Device Information
Once we have established a connection to the device, we can retrieve information from it. For example, we can retrieve the device’s hostname, serial number, and running configuration.
python
hostname = connection.send_command('show run | include hostname')
serial_number = connection.send_command('show inventory | include SN')
running_config = connection.send_command('show running-config')
In this example, we use the send_command method of the connection object to execute specific commands on the device. The output of each command is stored in a variable for further use.
Step 4: Configuring Network Devices
Now that we have retrieved device information, let’s move on to configuring devices. We can use Python to send configuration commands to the device and make changes. ```python config_commands = [ ‘interface GigabitEthernet0/1’, ‘ip address 192.168.0.2 255.255.255.0’, ‘no shutdown’, ]
output = connection.send_config_set(config_commands)
``` In this example, we define a list of configuration commands that we want to send to the device. We then use the `send_config_set` method to send these commands to the device. The output of the configuration is stored in the `output` variable.
Step 5: Error Handling and Troubleshooting
When working with network devices, it’s essential to handle errors and troubleshoot any issues that may arise. Let’s look at an example of error handling when establishing the connection. ```python from netmiko import SSHException
try:
connection = ConnectHandler(**device)
except SSHException as e:
print(f"Unable to establish SSH connection: {str(e)}")
``` In this example, we use a `try-except` block to catch any SSH connection exceptions. If an exception occurs, we print an error message to the console.
Step 6: Frequently Asked Questions
Q: Can I use this method to configure devices from different vendors?
Yes, the netmiko library supports a wide range of network devices from various vendors.
Q: Can I automate configuration changes on multiple devices simultaneously? Yes, you can iterate over a list of devices and perform similar configuration changes simultaneously.
Q: Is it possible to schedule these scripts to run automatically? Yes, you can use tools like cron or task scheduler to schedule the execution of these scripts periodically.
Conclusion
In this tutorial, we have learned how to automate network configuration tasks using Python. We explored how to establish SSH connections, retrieve device information, and configure network devices. Python provides a powerful and flexible way to automate sysadmin tasks, making network management more efficient and reliable.
Remember to always test your scripts in a lab environment before applying them to production devices. With practice and experience, you can expand on these examples to automate more complex network configurations.