Configure Azure SQL Database Firewall

This document provides a comprehensive guide to configuring the firewall for your Azure SQL Database. A well-configured firewall is crucial for securing your database by controlling network access.

Understanding Firewall Rules

Azure SQL Database firewall rules enable you to specify which IP address ranges are allowed to connect to your Azure SQL Database server. These rules can be set at the server level or at the database level.

Server-Level Firewall Rules

Server-level firewall rules apply to all databases hosted on your Azure SQL Database server. They are the primary mechanism for controlling access from external networks.

Creating Server-Level Rules using Azure Portal

1. Navigate to your Azure SQL Database server in the Azure portal.
2. In the left-hand menu, under "Security", select "Networking".
3. Go to the "Firewall rules" tab.
4. Click "Add firewall rule".
5. Provide a name for the rule (e.g., "OfficeIP").
6. Enter the "Start IP" and "End IP" addresses for the range you want to allow.
7. To allow your current IP address, click "Add your current client IP address".
8. Click "Save".

Creating Server-Level Rules using Azure CLI

You can manage firewall rules using the Azure Command-Line Interface (CLI).

Creating Server-Level Rules using PowerShell

Alternatively, you can use Azure PowerShell.

Database-Level Firewall Rules

Database-level firewall rules offer finer-grained control and apply only to a specific database. This is useful when you need to grant access to a particular database for certain IP addresses while denying access to others on the same server.

Enabling Database-Level Firewall Rules

Database-level firewall rules are configured within the specific database's settings in the Azure portal.

1. Navigate to your Azure SQL Database in the Azure portal.
2. In the left-hand menu, under "Settings", select "Firewall".
3. Ensure "Allow Azure services and resources to access this server" is configured appropriately (usually enabled for internal Azure services).
4. You can then add specific IP addresses or ranges for database-level access.

Allowing Azure Services

You can configure your firewall to allow other Azure services (like Azure Virtual Machines, Azure Functions, etc.) to connect to your Azure SQL Database. This is typically managed via the server-level networking settings.

Best Practices for Firewall Configuration

• Use Private Endpoints: For enhanced security, consider using Private Endpoints to establish a private connection from your virtual network to Azure SQL Database, bypassing the public internet.
• Regularly Review Rules: Periodically review your firewall rules to ensure they are still necessary and correctly configured. Remove any obsolete rules.
• Use Named Rules: Assign descriptive names to your firewall rules (e.g., "DeveloperMachine", "WebTierServers") to easily identify their purpose.
• Secure Your Client IP: If you need to allow access from your local machine, use the "Add your current client IP address" option, but be aware that your public IP can change. Consider using static IPs or VPNs for more stable access.

Troubleshooting Firewall Issues

If you encounter connection issues, verify the following:

• Your client IP address is correctly listed in a server-level or database-level firewall rule.
• The IP address range is accurate.
• There are no conflicting rules preventing access.
• Azure services that need to connect are explicitly allowed.

For detailed troubleshooting steps, refer to the Azure SQL Database connectivity troubleshooting guide.