SQL Server Security Basics | What is Authentication?

By definition Authentication means the process of verifying the identity of a user or process. If a user wants to talk to the database, SQL Server asks “Who you are?”, and authenticates you. There are three types of authentication modes available:

  • Windows Authentication
  • SQL Server Authentication
  • Azure Active Directory

Windows Authentication

  • This is the default authentication mode and the more secure as compared to SQL Server Authentication.
  • Microsoft BOL recommends to use Windows Authentication over SQL Server Authentication.
  • This mode is available both on SQL Server running on-premises and Azure Virtual Machine.
  • It uses Kerberos security protocol.
  • Connection made under this mode is also called “Trusted Connection” as SQL Server trusts Windows credentials.
  • Has additional password policy, such as strong password validation, support for account lock and password expiration.

SQL Server Authentication

  • Logins here are validated which are created and managed by SQL Server.
  • Unlike Windows Authentication, user should provide credentials every time while connecting to SQL Server.
  • There are few (optional) password policies also available.
  • This mode can be used where there is a requirement to support mixed operating system for applications and users cannot be validated using Windows domain.
  • Can be useful with web-applications where users have the provision to create their own identities.
  • It does not use Kerberos security protocol, and there is also a risk for applications that connect automatically with the SQL Server may save the password in file in clear text.

Azure Active Directory

  • This authentication mechanism validates an identity based on Azure Active Directory (Azure AD).
  • It supports token-based authentication, ADFS (domain federation) and/or built-in vanilla authentication without domain synchronization.
  • It can also support mechanism of password rotation in a single place.
  • Allows management of identities centrally (Central ID), which helps in simplifying user and permission management.

I am going to write a series of blogs on security basics, this one is first one in the row. Stay tuned.

References:

Choosing Authentication Mode

Azure AD Authentication

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