Security Considerations for SQL Server in Azure Virtual Machines
This topic includes overall security guidelines that help establish secure access to SQL Server instances in an Azure virtual machine (VM).
Azure complies with several industry regulations and standards that can enable you to build a compliant solution with SQL Server running in a virtual machine. For information about regulatory compliance with Azure, see Azure Trust Center.
Azure has two different deployment models for creating and working with resources: Resource Manager and classic. This article covers using both models, but Microsoft recommends that most new deployments use the Resource Manager model.
Control access to the SQL VM
When you create your SQL Server virtual machine, consider how to carefully control who has access to the machine and to SQL Server. In general, you should do the following:
- Restrict access to SQL Server to only the applications and clients that need it.
- Follow best practices for managing user accounts and passwords.
The following sections provide suggestions on thinking through these points.
When you create a SQL Server virtual machine with a gallery image, the SQL Server Connectivity option gives you the choice of Local (inside VM), Private (within Virtual Network), or Public (Internet).
For the best security, choose the most restrictive option for your scenario. For example, if you are running an application that accesses SQL Server on the same VM, then Local is the most secure choice. If you are running an Azure application that requires access to the SQL Server, then Private secures communication to SQL Server only within the specified Azure Virtual Network. If you require Public (internet) access to the SQL Server VM, then make sure to follow other best practices in this topic to reduce your attack surface area.
The selected options in the portal use inbound security rules on the VM's network security group (NSG) to allow or deny network traffic to your virtual machine. You can modify or create new inbound NSG rules to allow traffic to the SQL Server port (default 1433). You can also specify specific IP addresses that are allowed to communicate over this port.
In addition to NSG rules to restrict network traffic, you can also use the Windows Firewall on the virtual machine.
If you are using endpoints with the classic deployment model, remove any endpoints on the virtual machine if you do not use them. For instructions on using ACLs with endpoints, see Manage the ACL on an endpoint. This is not necessary for VMs that use the Resource Manager.
Finally, consider enabling encrypted connections for the instance of the SQL Server Database Engine in your Azure virtual machine. Configure SQL server instance with a signed certificate. For more information, see Enable Encrypted Connections to the Database Engine and Connection String Syntax.
Use a non-default port
By default, SQL Server listens on a well-known port, 1433. For increased security, configure SQL Server to listen on a non-default port, such as 1401. If you provision a SQL Server gallery image in the Azure portal, you can specify this port in the SQL Server settings blade.
To configure this after provisioning, you have two options:
For Resource Manager VMs, you can select SQL Server configuration from the VM overview blade. This provides an option to change the port.
For Classic VMs or for SQL Server VMs that were not provisioned with the portal, you can manually configure the port by connecting remotely to the VM. For the configuration steps, see Configure a Server to Listen on a Specific TCP Port. If you use this manual technique, you also need to add a Windows Firewall rule to allow incoming traffic on that TCP port.
Specifying a non-default port is a good idea if your SQL Server port is open to public internet connections.
When SQL Server is listening on a non-default port, you must specify the port when you connect. For example, consider a scenario where the server IP address is 188.8.131.52 and SQL Server is listening on port 1401. To connect to SQL Server, you would specify
184.108.40.206,1401 in the connection string.
You don't want attackers to easily guess account names or passwords. Use the following tips to help:
Create a unique local administrator account that is not named Administrator.
Use complex strong passwords for all your accounts. For more information about how to create a strong password, see Create a strong password article.
By default, Azure selects Windows Authentication during SQL Server Virtual Machine setup. Therefore, the SA login is disabled and a password is assigned by setup. We recommend that the SA login should not be used or enabled. If you must have a SQL login, use one of the following strategies:
Create a SQL account with a unique name that has sysadmin membership. You can do this from the portal by enabling SQL Authentication during provisioning.
If you do not enable SQL Authentication during provisioning, you must manually change the authentication mode to SQL Server and Windows Authentication Mode. For more information, see Change Server Authentication Mode.
If you must use the SA login, enable the login after provisioning and assign a new strong password.
Follow on-premises best practices
In addition to the practices described in this topic, we recommend that you review and implement the traditional on-premises security practices where applicable. For more information, see Security Considerations for a SQL Server Installation
If you are also interested in best practices around performance, see Performance Best Practices for SQL Server in Azure Virtual Machines.
For other topics related to running SQL Server in Azure VMs, see SQL Server on Azure Virtual Machines overview. If you have questions about SQL Server virtual machines, see the Frequently Asked Questions.
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