A Comprehensive Guide to VPC Peering in GCP and Azure

This content originally appeared on DEV Community and was authored by Daberechi

Introduction

VPC peering is a powerful networking feature that enables private communication between two Virtual Private Clouds (VPCs) within or across cloud providers. This guide covers:

• What VPC peering is
• Key benefits
• Step-by-step setup in GCP and Azure -Best practices and considerations

1. What is VPC Peering?

VPC peering (or VNet peering in Azure) establishes a direct, private connection between two VPCs using internal IP addresses. Traffic stays within the cloud provider’s backbone, avoiding public internet exposure.

GCP: Called VPC Network Peering.

Azure: Called Virtual Network (VNet) Peering.

1. Advantages of VPC Peering

i. Secure & Private: No public internet exposure.
ii. Low Latency: Traffic routes through the cloud provider’s internal network.
iii. Cost-Efficient: Avoids data transfer fees over public networks.
iv. Simplified Architecture: No need for VPNs or NAT gateways.
V. Global Reach (GCP): Supports cross-region peering.

Now, let’s dive into creating our VPC peering

Step 1: Creating of Projects
We are going to create two projects in our GCP because we want to peer VMs across different GCP projects.

• Login to your Google console
• Navigate to Resources Group
• Click on manage resources
• Click on new project

• Let’s name it project-a
• Create
• Create another project by following the above steps and name it project-b

Step 2: Set Up VPC Networks & Subnets

• Go to your project-a and click it
• Search VPC network and click it

• Click on create VPC
• Let’s name it vpc-a
• under subnets, let’s name the subnet subnet-a
• Choose your region
• Under IP stack, choose IPV4 (single stack)
• Put the IP address (10.0.0.0/24)

• Then create

• Go to your project-b

• Search VPC network and click on it

• Click create VPC

• Let’s name it vpc-b

• Subnet section, let’s name the subnet subnet-b

• Choose your region

• Under IP stack, choose IPV4 (single stack)

• Put the IP address (192.168.0.0/24)
  Then create
  Note: Ensure that the two VPC and subnets must not have the same IP address to avoid overlap

Step 3: Launch VMs in Each VPC

• Go to your project-a and click on it
• Search compute engine
• Click on create instance

• Let’s name it VM-a
• Choose your region and zone
• Scroll down to boot disk
• Click on change
• Under operating system, select the OS you want. I will be using Ubuntu
• Click on select
• Click on advance
• Click on network
• Click on vpc-a
• Click on create

Create VM for project-b
Follow the above steps

• Name it VM-b
• Network is vpc-b

Step 4: Configure Firewall Rules

• Go to your project-a, search VPC network and click on it
• Click on firewalls
• Click on create firewalls rule
• Let’s name it allow-vpc-peering
• Scroll down to target, select all instance in the network
• Under source filter, leave it at IPV4 range
• Under source IP, put 192.168.0.0/24 ( Project-b’s subnet)
• Under protocol and port, put Allow all (for testing) or if you want to restrict, select TCP, then put 22 (SSH)

• Click on other, and type ICMP

-Go to your project-b and repeat the above steps

• Name it allow-vpc-peering
• Source IP, put 10.0.0.0/24 (project-a subnet)

Step 5: Establish VPC Peering

• Go to your project-a
• Search VPC network
• Click on vpc-a peering
• Click create VPC connection
• Click continue

• Let’s name it peer-a-to-b
• In VPC network, select your vpc-a
• In peer VPC network, select “in another project”
• Go to your project-b, click it and copy the ID
• Paste it under “in peer VPC network” in your project-a

• Type vpc-b in VPC network name
• Configure Routes by enabling ” Export custom routes” and “Import custom routes”
• Create

Go to your project-b

• search VPC network, then click VPC peering
• Click on create connection
• Click continue
• Let’s name it peer-b-to-a
• Your VPC network, choose vpc-a
• Choose another network
• Then put the ID of project-a
• Then put vpc-a under name of vpc network
• Configure Routes by enabling “Export custom routes” and “Import custom routes”
• Click create

Step 6: Test Connectivity

• Go to your project-a
• Search compute engine
• Click VM instance
• Click on SSH
• Ping VM-b internal IP by typing ping 192.168.0.2

• Test SSH by typing ssh @192.168.0.2

• Go to your project-b

• Search compute engine

• Click on VM instance

• Click on SSH

• Ping VM-a internal IP by typing ping 10.0.0.2

• Test SSH by typing ssh @10.0.0.2

Now that we are done with GCP, let’s move on to Azure peering

Step 1: Firstly, create a Resource group

Step 2: Create two Vnet ( Virtual Network)

• Go to your Azure portal
• Search and click on virtual networks
• Click on create

• Choose your resource group
• Let’s name our Vnet Vnet-a
• Choose your region
• click on IP address
• Delete the default IP address and click on add subnet
• Let’s name the subnet subnet-a
• Click on review+create
• Create

Create another Virtual Network

• Choose the same resources group
• Let’s name it Vnet-b
• Maintain the same region
• Click on security and enable encryption
• Click on IP address
• Put an IP address (192.168.0.0/16)
• Choose /16 in the next space
• Delete the default IP address and click on add subnet
• Let’s name the subnet subnet-b
• Click on review+create
• Then create

Steps 3: Let’s deploy VMs

• Go to your Azure portal
• Search and click on virtual machine
• Click on create

• Choose your resource group
• Let’s name our VM VM-a
• Under image, I will select Ubuntu 20.04
• Enable _x64
• Under authentication type, use SSH key
• Give your VM a username
• Open powershell and create SSH key (ssh-keygen -t rsa -b 4096)
• Copy the public SSH key
• Go back to your VM creation page
• Click on the drop-down button in ssh public key source and select use existing public key
• Paste the SSH public key you copied
• Go to network
• Select your Vnet-a in virtual networks section
• Scroll down and enable delete public IP and NIC when VM is deleted
• Click review+create
• Create

Create another Virtual Machine for Vnet-b
Repeat the above steps

Step 3: Creating ICMP and SSH firewall rules in the two vms to allow pinging

• Click on VM-a
• Click on network settings
• Click on port rule
• Click on inbound port rule
• In destination, click ICMP
• Put Allow in Action
• Then click add

• Do it again for SSH

• Click on VM-b
  Repeat the above steps and configure the rules for VM-b

Steps 4: Create VNet Peering

• On your Azure portal, search and click on virtual networks
• Click on Vnet-a
• Click on settings and click on peering
• Click on add
• Let’s name it vnet-a-to-vnet-b

• Select Vnet-b in virtual networks
• Under local virtual networks summary, peering link name, put vnet-a-to-vnet-b
• Then add Do the same for VM-b

Step 5: Test the Connection

• Open your mobaxterm
• Copy the public IP address of any of the VM, put it in your mobaxterm (where you see host IP)
• Put your private SSH key
• Click ok
• Once you have successfully login, type sudo apt update
• then type hostname

• ping the public IP address of VM-b if you are logged in VM-a

Conclusion

We have come to the end of today’s section where we learn how to peer VMs in GCP and Azure.
Please try this steps and give me a feedback.
I am open to corrections and questions.

From your favorite girl
Dabbie

This content originally appeared on DEV Community and was authored by Daberechi