Protocols for MSSQLSERVER Properties (Advanced Tab)
Use the Advanced tab on the Protocols for MSSQLSERVER Properties dialog box to configure Extended Protection for Authentication for the SQL Server Database Engine. Extended Protection is a feature of the network components implemented by the operating system. Extended Protection is available in Windows 7 and Windows Server 2008 R2, and is included in service packs for older operating systems. SQL Server is more secure when connections are made using Extended Protection. Some benefits of Extended Protection require Force Encryption to be selected on the Flags tab.
Windows does not enable Extended Protection by default. For information about how to enable Extended Protection in Windows, see the Knowledge Base article, Extended Protection for Authentication.
For more information about how to configure other SQL Server services, and a complete description of Extended Protection, see more recent information on Microsoft.com.
Extended Protection is fully supported by the SQL Server Native Client beginning with SQL Server 2008 R2. Support for Extended Protection for other SQL Server client providers is not currently supported.
There are three possible values:
When set to Off, Extended Protection is disabled. The instance of SQL Server will accept connections from any client regardless of whether the client is protected or not. Off is compatible with older and unpatched operating systems, but is less secure. Only use this setting when you know that the client operating systems do not support extended protection.
When set to Allowed, Extended Protection is required for connections from operating systems that support Extended Protection. Connections from unprotected client applications that are running on protected client operating systems are rejected. Extended Protection is ignored for connections from unprotected operating systems. This setting is more secure than Off, but is not the most secure setting. Use this setting in mixed environments, where some operating systems or applications support Extended Protection and some do not.
When set to Required, only connections from protected applications on protected operating systems are accepted. This setting is the most secure of the three options but connections from operating systems that do not support Extended Protection will not be able to connect to SQL Server.
Accepted NTLM SPNs
When the instance of SQL Server is identified by more than one NTLM service principal name (SPN), list the SPNs here as a series of strings separated by semicolons. For example, the value MSSQLSvc/HostName1.Contoso.com;MSSQLSvc/HostName2.Contoso.com, indicates that clients attempting to connect to SPNs named MSSQLSvc/HOST1.Contoso.com and MSSQLSvc/HOST2.Contoso.com are allowed. The variable has a maximum length of 2048 characters.