Azure Private Link and VNet Integration Overview

Introduction

Azure Private Link is a networking service that enables you to access Azure platform services (e.g., Azure Storage, Azure SQL Database) and Azure hosted customer-owned/partner services over a private endpoint within your virtual network. Traffic between your virtual network and the service travels the Microsoft backbone network, eliminating exposure to the public internet.

This document provides an overview of Azure Private Link and its integration with Azure Virtual Networks (VNets), focusing on how it enhances security and simplifies connectivity for your applications.

Azure Private Link Concept

Azure Private Link allows you to provision a private endpoint in your virtual network. This private endpoint maps to a specific service instance in Azure. Once created, you can access the service from your virtual network via a private IP address from your virtual network address space. This ensures that all traffic stays within your private network or the Microsoft backbone network.

Diagram illustrating Azure Private Link architecture.

Key Components:

Private Link Service: A service that exposes your Azure PaaS service or your own service to be consumed via Private Link.
Private Endpoint: A network interface that uses a private IP address from your virtual network, effectively bringing the service into your network.
Connection: The secure tunnel established between the private endpoint and the service.

Virtual Network (VNet) Integration

Azure Virtual Networks provide a fundamental building block for your private network in Azure. They allow you to create isolated and secure network environments for your Azure resources. Private Link leverages this VNet infrastructure to provide secure, private access to services.

When you deploy a private endpoint, it resides within a specific subnet of your virtual network. Azure handles the network routing and DNS resolution to ensure that requests originating from your VNet are directed to the private endpoint, and subsequently to the targeted service.

How VNet Integration Works:

A private endpoint is created within a subnet of your Azure VNet.
A private IP address is assigned to the network interface of the private endpoint from the subnet's address range.
Azure DNS is configured to resolve the service's FQDN (Fully Qualified Domain Name) to the private IP address of the private endpoint for resources within your VNet.
All traffic destined for the service is routed through the private endpoint within your VNet, bypassing public endpoints and the internet.

Important: Ensure your VNet has proper DNS resolution configured (typically Azure Private DNS Zone) to enable seamless private endpoint connectivity.

How It Works

The process of establishing private connectivity involves the following steps:

Create a Private Endpoint: You initiate the creation of a private endpoint in your chosen virtual network and subnet.
Select the Target Service: You specify the Azure service (or a customer/partner service) you wish to connect to.
Approve Connection: For Azure platform services, the connection is usually automatic. For customer-owned services, the service owner needs to approve the connection request.
DNS Configuration: Azure automatically configures the necessary DNS records in a private DNS zone associated with your VNet. This ensures that applications within your VNet resolve the service's FQDN to the private IP address of the private endpoint.
Private Connectivity: Your applications can now access the service using its standard FQDN, and all traffic will be routed securely over the Microsoft backbone network to the private endpoint.

Key Benefits

Enhanced Security: Eliminates exposure of services to the public internet, reducing the attack surface.
Simplified Network Architecture: No need for complex network setups like VPNs or ExpressRoute for accessing Azure services privately.
Consistent Management: Manage access to services using familiar Azure networking constructs.
Data Exfiltration Protection: Prevents data leakage by restricting access to services only from within your private network.
Broad Service Support: Works with a wide range of Azure platform services and custom applications.

Common Use Cases

Accessing Azure SQL Database or Azure Cosmos DB from an application deployed in an Azure VNet without exposing the database to the internet.
Connecting to Azure Storage accounts (Blob, Files, Queues, Tables) privately for secure data operations.
Enabling secure access to Azure Kubernetes Service (AKS) private clusters.
Connecting to Azure Key Vault for secure management of secrets.
Exposing your own custom applications running on Azure to other VNets privately.

Getting Started

To get started with Azure Private Link and VNet integration:

Ensure you have an Azure virtual network set up.
Identify the Azure service you want to access privately.
Navigate to the target service in the Azure portal or use Azure CLI/PowerShell.
Create a private endpoint, selecting your VNet, subnet, and the target service.
Configure the associated Azure Private DNS Zone (if not done automatically).
Update your application's connection strings or configurations to use the service's FQDN.

Refer to the official Azure Private Link documentation for detailed configuration steps and supported services.