How to Use Azure Private Link

Step-by-step guides and best practices for implementing Azure Private Link.

Overview of Implementation Steps

Azure Private Link enables you to access Azure Platform as a Service (PaaS) and Azure hosted customer-owned services over a private endpoint in your virtual network. This is a fundamental step towards securing your network traffic and reducing exposure to the public internet.

1

Create a Private Endpoint

The first major step is to provision a private endpoint resource within your virtual network. This endpoint will act as the network interface for your private link service.

Key considerations:

  • Ensure the private endpoint is created in the same region as your virtual network.
  • Specify the target resource ID for the Azure service you want to connect to.

You can create a private endpoint using the Azure portal, Azure CLI, PowerShell, or ARM templates.

# Example using Azure CLI
az network private-endpoint create \
  --name MyPrivateEndpoint \
  --resource-group MyResourceGroup \
  --vnet-name MyVnet \
  --subnet MySubnet \
  --private-connection-resource-id "/subscriptions/YOUR_SUBSCRIPTION_ID/resourceGroups/MyServiceResourceGroup/providers/Microsoft.Storage/storageAccounts/mystorageaccount" \
  --group-ids "blob" \
  --location "eastus"
2

Configure DNS Resolution

Proper DNS configuration is crucial for Private Link to function correctly. When you create a private endpoint, Azure typically creates a private DNS zone and links it to your virtual network. However, you might need to manage or verify these settings.

Tasks:

  • Ensure the service's FQDN (Fully Qualified Domain Name) resolves to the private IP address of the private endpoint.
  • If using custom DNS servers, create A records or CNAME records in your DNS zone pointing to the private IP.
Important: For services like Azure Storage, you might have multiple sub-resources (e.g., blob, file, queue). Ensure DNS is configured for all relevant sub-resource group IDs.
3

Connect and Verify

Once the private endpoint is deployed and DNS is configured, you can test connectivity from a resource within your virtual network.

Verification steps:

  • Use tools like ping, nslookup, or even the service's SDK to attempt a connection.
  • Check the status of the private endpoint connection in the Azure portal.

Advanced Scenarios & Best Practices

Private Link for Your Own Services

You can also expose your own applications hosted on Azure (e.g., in AKS, App Service, VMs) using Azure Private Link Service. This involves creating a Private Link Service resource that references your network load balancer.

Network Security Groups (NSGs)

While Private Link secures traffic within Azure, ensure your NSGs are configured to allow traffic to the subnet where your private endpoint resides. For outbound traffic from your subnet, you might need rules to permit access to the private endpoint's IP.

Firewall Rules

If the target Azure service has a firewall configured (e.g., Azure Storage firewall), ensure it's set to "Allow access from trusted Microsoft services" or specifically allow traffic from your virtual network's subnet. When using Private Link, you can often restrict the service's firewall to disallow public network access entirely.

Monitoring and Logging

Leverage Azure Monitor and diagnostic logs for both your private endpoint and the target service. This helps in troubleshooting connectivity issues and auditing access patterns.

Troubleshooting Common Issues