Last updated on Nov 21, 2023
Two different authentication methods can be used to connect to SQL Server. They are Windows authentication and SQL Server authentication.
The user needs to authenticate to Windows with the user ID and password For Windows authentication. When the user has authenticated to Windows, they will be able to connect to SQL Server through Windows authentication, i.e., provided that their Windows account was allowed to access SQL Server through a connection. Windows authentication is closely connected to Windows Security and is referred to as Integrated Security. Windows authentication is perfect when someone belongs to a windows domain.
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But what if we are unable to connect to Windows? Then SQL authentication can be used. In comparison with Windows authentication, SQL authentication is less secure. To connect to the SQL server through SQL authentication, we must use our user Id and password while logging in. SQL Authenticated login password is saved in the master database. As the password is saved in an SQL database, it will be easier to hack it. We can back up and restore it with a database backup. Therefore it is not as safe as using windows authentication.
Windows authentication is the default way to authenticate when you install an SQL Server instance. To support SQL authentication, we must set up SQL Server for supporting mixed-mode authentication. While we are using mixed mode, Windows and SQL authentication may be used for logging into SQL Server. If SQL Server does not support mixed mode, then Windows accounts are allowed to connect to SQL Server. Since SQL authentication is not as secure as Windows authentication, it is recommended that only the instance of the SQL server should be configured for supporting mixed-mode if you need to support users or apps that are unable to connect to Windows. Although Windows authentication is safer and the preferred practice for connection to SQL Server, many customized application software providers still do not support connection through Windows authentication.
During the installation of SQL Server, we have the option of supporting only Windows authentication or the two authentication methods, which is referred to as mixed mode. At the time of installation, we need to decide whether to use mixed-mode or not during the definition of the database engine configuration.
By default, Windows authentication is selected. When we choose Windows authentication, the SA account will be disabled. If we want to choose both SQL Server and Windows authentication, then we need to choose the Mixed-mode option. After choosing the Mixed-mode option, SA account password boxes will be enabled, and you need to provide a password for the SA account. While using the mixed-mode, we may disable the SA account after enabling it to secure the SA account.
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There are several ways to check which authentication method is set up. One such method is the use of SQL Server Management Studio (SSMS). For using SSMS, we need to right-click on the Instance name and choose the properties option. When we do it on the instance, the properties page will be displayed.
Determining the authentication mode: The radio button must be enabled to select the mode of authentication; if the radio button is enabled at mixed mode, then its mode of authentication is the mixed mode. An alternative way to verify what authentication modes are configured is by using the TSQL code.
1 -> Windows authentication only
0 -> Windows and SQL Server Authentication
Sometimes we need to change the authentication settings of a SQL Server instance. This can happen if we use the default settings while installing to support Windows authentication and later acquire certain software which will be connected through SQL Server authentication. Alternatively, we may want to make our instance more secure by deleting support for SQL Server authentication. Authentication options may be modified easily by using the SSMS properties page.
If we need to modify my instances to only support Windows authentication, then click on the "Windows authentication mode" button and then select the "OK" button to implement this modification. Once it is done, we need to restart my instance in order for that change to become effective.
To connect to SQL Server, Access to SQL Server is required. The Access is provided through a login. Login is also referred to as security principal and is saved in the master database. One exception is to Have Access to a contained database. With the databases contained, users log in directly into the database without it being necessary to log into the master database.
Three kinds of logins are saved in the master database. They are SQL, Windows user, and windows group. Let us go through each of the logins in detail.
A Windows user login allows Access to only one Windows user. During the creation of this type of connection, no password is required to set the connection in SQL Server. This kind of login needs the user to validate their login by logging in to the windows domain. The password is stored in the windows domain.
SQL Server login is the same as Windows user login. In windows, user login access is given to only one Windows user, while for an SQL server login, the password to SQL login will be stored in the master database. Therefore, during the configuration of an SQL Server login, a password must be given for the login, as well as some other password options. SQL Server login should be enabled to apply the password policies, and the expiration of windows and may require that a user needs to change the password when logging in for the first time. These features were introduced in SQL server 2005. For apps that support these new password functionality, they may use the API NetValidatePasswordPolicy.
The last kind of login is windows group login. It is the same as windows login but quite different from it. A Windows group login allows us to access an SQL Server instance for each Windows login which is a group member. Windows groups are an excellent way of providing Access to multiple windows logins without just having to set one login in SQL server. Through a Windows group, accessing the SQL Server instance may be maintained by adding or deleting members of the group. The use of Windows groups minimizes security management efforts and resolves security problems associated with the connection.
The default database setting for making a connection is the "master" database. During login configuration, the default database can be modified for any database on the server. The best practice is to define the default database to a database to be used by the user when logging into SQL Server.
Windows logins are considered to be more secure as a result of how the login password is stored. The Windows login password is stored through true encryption. When a SQL Login password is not encrypted, it is hashed instead. As the SQL login is hashed, it is easier to crack the password. Windows connections need domain administrators to configure the login and password, while SQL logins database administrators for configuring the login and password. Having the domain administrator's login password management offers another layer of security, commonly known as separation of duties. Separating the Windows login creation and management tasks from database management and database access provides extra security controls for accessing data stored within SQL Server.
Creating an SQL Server login enables users to log in to SQL Server. However, a single connection does not allow users to access data in the various databases of the server. To be able to read or write data in a database, a user must have Access to one or more databases. A connection may be configured to access multiple databases in one instance if necessary.
In this blog, we have learned about SQL server Authentication. We hope you found this information helpful. If you are looking for any information related to SQL server authentication, feel free to comment in the comment section. We will get back to you with that information.
As a senior Technical Content Writer for HKR Trainings, Gayathri has a good comprehension of the present technical innovations, which incorporates perspectives like Business Intelligence and Analytics. She conveys advanced technical ideas precisely and vividly, as conceivable to the target group, guaranteeing that the content is available to clients. She writes qualitative content in the field of Data Warehousing & ETL, Big Data Analytics, and ERP Tools. Connect me on LinkedIn.
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