Troubleshoot Azure Private Link

This document provides guidance on common issues and troubleshooting steps for Azure Private Link connections.

Common Issues and Solutions

Connectivity Problems

If you are experiencing connectivity issues to your private endpoint, consider the following:

DNS Resolution: Ensure that the DNS records for your service are correctly configured to resolve to the private IP address of the private endpoint. This often involves a Private DNS Zone in Azure.
Network Security Groups (NSGs): Verify that NSGs applied to the subnet of your private endpoint allow inbound traffic from your client's IP address or subnet to the required ports for your service.
Firewall Rules: Check any firewalls between your client and the private endpoint. Ensure that traffic is allowed.
Private Endpoint Status: Confirm that the private endpoint and its associated network interface are in a 'Succeeded' provisioning state in the Azure portal.

Service Endpoint Conflicts

In some cases, you might have configured Service Endpoints on the same subnet as your Private Endpoint. While not always a conflict, it's important to understand the implications.

Service Endpoints use public IP addresses of the Azure service, whereas Private Endpoints use private IP addresses.
Ensure your service configuration is set to accept private endpoints and/or deny public access if desired.

Access Denied Errors

If you are receiving "Access Denied" errors, this typically points to an authorization or networking issue.

RBAC Permissions: Verify that the identity (user, service principal, managed identity) attempting to access the resource via the private endpoint has the necessary Role-Based Access Control (RBAC) permissions on the target Azure resource.
Service-Side Firewall/Access Policies: Some Azure services have their own access control mechanisms (e.g., Storage Account firewall, Key Vault access policies). Ensure these are configured to allow access from your client's VNet or specific IP ranges.

Troubleshooting Tools and Techniques

Leverage these tools to diagnose problems:

nslookup or dig: Use these command-line tools from your client to verify DNS resolution for the service FQDN.
nslookup your-service.privatelink.your-region.azurewebsites.net
ping (limited use): While ping might not work for all services (especially those that don't respond to ICMP), it can sometimes indicate basic network reachability.
telnet or nc (netcat): Use these to test connectivity to the specific port the service uses.
telnet your-service.privatelink.your-region.azurewebsites.net 443
Azure Network Watcher: Utilize features like IP Flow Verify and Connection Troubleshoot to diagnose NSG and route issues.
Connection Troubleshoot: A feature within Network Watcher that helps determine if a VM can connect to a specific endpoint.

Important Note on Private Endpoint IP Allocation

When you create a private endpoint, Azure automatically assigns a private IP address from the subnet you select. You cannot manually assign this IP. Ensure your subnet has sufficient available IP addresses.

Specific Service Troubleshooting

For issues related to specific Azure services, refer to their respective documentation:

If you continue to experience issues, consider opening a support ticket with Microsoft Azure.