Detailed Guide to Provision AWS Network Firewall using Terraform

Introduction

AWS Network Firewall is the recently launched, fully managed, highly available, and scalable managed network by AWS, providing security for the VPC’s workloads. AWS Network Firewall works together with AWS Firewall Manager so you can build policies based on AWS Network Firewall rules and then centrally apply those policies across your VPCs and accounts. In the previous blog, we learned about detailed Manual Provisioning of AWS Network Firewall.

Today, we will automate the Provisioning of AWS Network Firewall using Infrastructure as a code DevOps Tool, i.e., Terraform.

Advantages of Terraform:

• Terraform is an open-source Infrastructure-as-Code (IaC) software tool that enables us to create, update and improve Infrastructure in many Cloud Platforms like AWS, Azure, and GCP.
• Terraform Support Reuse of the code.
• We can Provision many numbers physical resources with a single command.
• Terraform has Idempotent property. That is, the state of the infrastructure is saved in local machines. The second application results in 0 changes.

Learn more about Continuous Integration to Automate Terraform modules with GitHub Action as IaC Pipelines here.

Prerequisites

• Any Linux instances
• AWS root account
• Terraform should be Preinstalled in the Linux machine
• AWS CLI

AWS Services Used

• AWS Network Firewall
• AWS Network Firewall policy
• AWS Network Firewall Rule Groups
• VPC
• Subnets
• Route Table
• Internet Gateway
• Windows instance

Deployment Architecture

Step by Step Guide to Execute the Terraform Code

We are going to Construct the Terraform code in the Linux machine in Modular Format then we execute the code using Terraform Commands.

Step 1: Go to a Linux Instance and connect to an AWS account using AWS CLI.

Step 2: Create a Folder called “NetworkFirewall” and go into the folder.

Step 3: Type Git init to initiate the Git repo to pull the code from GitHub.

Go to NetworkFirewall Folder

Step 4: Go to FirewallTerraform  Folder

Step 5: Here you can see the Files Folders.

File Main.tf

The use of main.tf file is used to put the code in Modular format.

Run the Below Code to see the code.

File Var.tf 

This File contains all the variables declared in the Terraform Code. The code Reusability is achieved here. If we change the values in the variable. We can use the same code to provision similar infrastructure.

File Provider.tf – This File contains the CloudProvider details.

Step 6: Now Go into the module Folder by running the below code.

Here you will see two folders, Firewall, and Networking. Here we are segregating the Resource to the provision in the AWS platform in a modular way. Go into each folder and check the Files present.

Step 7: Now Go back to the Folder where main.tf File is presently using the below command.

Execute the below Code

Initialize the terraform code.

Output: If no errors.

Execute the below code to preview the action Terraform would take to modify your Infrastructure.

Output: If not Errors.

Execute the below Code:

The terraform apply command performs a plan just like terraform plan does, but then actually carries out the planned changes to each resource using the relevant infrastructure provider’s API.

You will get the output in this way. Provisioning AWS Network Firewall using terraform started.

Step 8: Check and verify the newly provisioned resources in the AWS console.

VPC

Subnets

Route Table

Internet Gateway

Firewall

Firewall Policy

Firewall Rule Group

Step 9: Create an windows instance in Firewall-VPC in Resource subnet. Try to access the blocked domain name in the browser. You will find error page or page not found.

Step 10: Destroy the Infrastructure using the below command.

If you get any errors, Try again the same command.

Conclusion

Provisioning infrastructure on the cloud using Terraform gives us more grip on the infrastructure and fewer manual tasks. The configuration language is human-readable, making us write the infra code more quickly. This allows us to track resource changes or any updates throughout the deployment.

About CloudThat