How to: Configure Login Auditing (SQL Server Management Studio)
Use login auditing to monitor SQL Server Database Engine login activity.
Login auditing can be configured to write to the error log on the following events.
Failed logins
Successful logins
Both failed and successful logins
You must restart SQL Server before this option will take effect.
To configure login auditing
In SQL Server Management Studio, connect to an instance of the SQL Server Database Engine with Object Explorer.
In Object Explorer, right-click the server name, and then click Properties.
On the Security page, under Login auditing, click the desired option and close the Server Properties page.
In Object Explorer, right-click the server name, and then click Restart.