Book Image

Python Network Programming Techniques

By : Marcel Neidinger
Book Image

Python Network Programming Techniques

By: Marcel Neidinger

Overview of this book

Network automation offers a powerful new way of changing your infrastructure network. Gone are the days of manually logging on to different devices to type the same configuration commands over and over again. With this book, you'll find out how you can automate your network infrastructure using Python. You'll get started on your network automation journey with a hands-on introduction to the network programming basics to complement your infrastructure knowledge. You'll learn how to tackle different aspects of network automation using Python programming and a variety of open source libraries. In the book, you'll learn everything from templating, testing, and deploying your configuration on a device-by-device basis to using high-level REST APIs to manage your cloud-based infrastructure. Finally, you'll see how to automate network security with Cisco’s Firepower APIs. By the end of this Python network programming book, you'll have not only gained a holistic overview of the different methods to automate the configuration and maintenance of network devices, but also learned how to automate simple to complex networking tasks and overcome common network programming challenges.

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Table of Contents (14 chapters)
Preface
Preface
Who this book is for
What this book covers
To get the most out of this book
Download the example code files
Code in Action
Download the color images
Conventions used
Get in touch
Reviews
Share Your Thoughts
1
Chapter 1: A Primer on Python 3
Chapter 1: A Primer on Python 3
Technical requirements
Assigning variables in Python
Converting between data types in Python
Looping over lists in Python
Controlling the flow of a Python program using if statements
Executing code until a condition is met using while loops
Writing reusable code with functions
Storing and accessing key-value pairs using dictionaries
Importing modules from the standard library
Installing modules from the PyPI
Free Chapter
2
Chapter 2: Connecting to Network Devices via SSH Using Paramiko
Chapter 2: Connecting to Network Devices via SSH Using Paramiko
Technical requirements
Initiating an SSH session with Paramiko
Executing a command via SSH
Reading the output of an executed command
Executing the same command against multiple devices
Executing a sequence of commands
Using public/private keys for authentication
Loading local SSH configuration
3
Chapter 3: Building Configuration Templates Using Jinja2
Chapter 3: Building Configuration Templates Using Jinja2
Technical requirements
Loading Jinja2 templates in Python
Passing variables from Python to a template
Writing your rendered template to a file
Using for-loops in Jinja2 to configure an access list
Creating a port configuration template using if-clauses in Jinja2
Creating modular templates using Jinja2's import methods
Using Python functions from within your template with Jinja2 filters
Structuring your configuration template with blocks and template inheritance
4
Chapter 4: Configuring Network Devices Using Netmiko
Chapter 4: Configuring Network Devices Using Netmiko
Technical requirements
Connecting to a network device using netmiko
Sending commands using netmiko
Retrieving command outputs as structured Python data using netmiko and Genie
Gathering facts using netmiko
Connecting to multiple devices
Creating and applying a configuration template with Jinja2 and netmiko
Copying files to a device using netmiko
Escalating privileges with netmiko
Authenticating using public-private keys with netmiko
Handling commands that prompt for information using netmiko
5
Chapter 5: Model-Driven Programmability with NETCONF and ncclient
Chapter 5: Model-Driven Programmability with NETCONF and ncclient
Technical requirements
Revisiting the NETCONF and YANG modules
Connecting to a network device using ncclient
Using NETCONF and ncclient to retrieve the running configuration
Using NETCONF and ncclient to change the starting configuration
Retrieving an interface configuration using NETCONF and ncclient
Changing an interface configuration using NETCONF and ncclient
Reacting to event notifications using NETCONF and ncclient
6
Chapter 6: Automating Complex Multi-Vendor Networks with NAPALM
Chapter 6: Automating Complex Multi-Vendor Networks with NAPALM
Technical requirements
Connecting to devices from different vendors using NAPALM
Issuing commands to a device using NAPALM
Testing network reachability using ping and NAPALM
Backing up your device configuration using NAPALM
Gathering facts about your network device using NAPALM
Creating and applying a configuration template with jinja2 and NAPALM
Rolling back configuration changes using NAPALM
Validating deployments using NAPALM
7
Chapter 7: Automating Your Network Tests and Deployments with pyATS and Genie
Chapter 7: Automating Your Network Tests and Deployments with pyATS and Genie
Technical requirements
Revisiting the concept of testing
Creating a pyATS testbed file
Connecting to your device and issuing commands using pyATS
Retrieving your device's current state using pyATS
Using Genie Conf objects to create a portable configuration script
Comparing your device's current state to a previously learned state
8
Chapter 8: Configuring Devices Using RESTCONF and requests
Chapter 8: Configuring Devices Using RESTCONF and requests
Technical requirements
Revisiting HTTP's request-response model and RESTCONF principles
Making HTTP requests using the requests module in Python
Retrieving all interfaces of a device using RESTCONF and requests
Creating a VLAN using RESTCONF and requests
Updating a VLAN using RESTCONF and requests
Deleting a VLAN using RESTCONF and requests
9
Chapter 9: Consuming Controllers and High-Level Networking APIs with requests
Chapter 9: Consuming Controllers and High-Level Networking APIs with requests
Technical requirements
Authenticating web requests
Storing authentication metadata between requests using sessions
Retrieving a list of Meraki networks
Retrieving usage details and connected clients for a Meraki network
Rebooting a Meraki device
Retrieving channel usage for your Meraki access point
Updating the switchport configuration of a Meraki device
Deleting the QoS rules on a Meraki device
Using webhooks to programmatically react to an AP going down
10
Chapter 10: Incorporating your Python Scripts into an Existing Workflow by Writing Custom Ansible Modules
Chapter 10: Incorporating your Python Scripts into an Existing Workflow by Writing Custom Ansible Modules
Technical requirements
Setting up the module structure
Documenting your module
Passing information into your module
Using Ansible's built-in functionality to do web requests
Packaging and calling your modules from Ansible playbooks
11
Chapter 11: Automating AWS Cloud Networking Infrastructure Using the AWS Python SDK
Chapter 11: Automating AWS Cloud Networking Infrastructure Using the AWS Python SDK
Technical requirements
Setting up the library to interact with your AWS account
Collecting information about your cloud networking resources
Starting EC2 instances
Creating a VPC
Subnetting your VPC
Changing routes in your VPC
12
Chapter 12: Automating your Network Security Using Python and the Firepower APIs
Chapter 12: Automating your Network Security Using Python and the Firepower APIs
Technical requirements
Exploring the API Explorer
Authenticating against the FMC REST API
Retrieving access policies
Changing access policies
Retrieving access rules
Changing access rules
Deleting access rules
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13
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To get the most out of this book

This book requires you to have a version of Python, preferably Python 3, installed. All scripts have been tested against Python version 3.8 on Mac OS X and Linux but should also work on Windows.

Chapter 7, Automating Your Network Tests and Deployments with pyATS and Genie, and Chapter 10, Incorporating Your Python Scripts into an Existing Workflow by Writing Custom Ansible Modules, use Python packages that are incompatible with Windows. To follow along with these chapters, you will have to use either the Windows Subsystem for Linux or a virtual machine running Linux. Any modern Linux distribution, such as CentOS/Fedora or Debian/Ubuntu, should work.

In addition, you'll need a network device to test your scripts against. This device can be physical, virtual, or part of a sandbox, but an admin user is required.

Chapter 11, Automating AWS Cloud Networking Infrastructure Using the AWS Python SDK, requires a Firepower Management console from Cisco, and Chapter 9, Consuming Controllers and High-Level Networking APIs with requests, requires a Cisco Meraki organization. The code in both chapters can be tested using the sandboxes available with the Cisco DevNet sandbox offerings.

If you are using the digital version of this book, we advise you to type the code yourself or access the code via the GitHub repository (link available in the next section). Doing so will help you avoid any potential errors related to the copying and pasting of code.

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