Azure Files supports identity-based authentication over Server Message Block (SMB) through on-premises Active Directory Domain Services (AD DS) and Azure Active Directory Domain Services (Azure AD DS). This article focuses on how Azure file shares can use domain services, either on-premises or in Azure, to support identity-based access to Azure file shares over SMB. Enabling identity-based access for your Azure file shares allows you to replace existing file servers with Azure file shares without replacing your existing directory service, maintaining seamless user access to shares.

Azure Files enforces authorization on user access to both the share and the directory/file levels. Share-level permission assignment can be performed on Azure Active Directory (Azure AD) users or groups managed through the Azure role-based access control (Azure RBAC) model. With RBAC, the credentials you use for file access should be available or synced to Azure AD. You can assign Azure built-in roles like Storage File Data SMB Share Reader to users or groups in Azure AD to grant read access to an Azure file share.

At the directory/file level, Azure Files supports preserving, inheriting, and enforcing Windows DACLs just like any Windows file servers. You can choose to keep Windows DACLs when copying data over SMB between your existing file share and your Azure file shares. Whether you plan to enforce authorization or not, you can use Azure file shares to back up ACLs along with your data.