Using Azure Active Directory with the ODBC Driver

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Purpose

The Microsoft ODBC Driver for SQL Server version 13.1 or above allows ODBC applications to connect to an instance of Azure SQL Database using a federated identity in Azure Active Directory. The identity can use a username/password, an Azure Active Directory access token, an Azure Active Directory managed identity (17.3+), or Windows-Integrated Authentication (17.6+ on Linux/macOS). For the ODBC Driver version 13.1, the Azure Active Directory access token authentication is Windows only. The ODBC Driver version 17 and above support this authentication across all platforms (Windows, Linux, and macOS). A new Azure Active Directory interactive authentication with Login ID is introduced in ODBC Driver version 17.1 for Windows. A new Azure Active Directory managed identity authentication method was added in ODBC Driver version 17.3.1.1 for both system-assigned and user-assigned identities. All of these options are accomplished by using new DSN and connection string keywords, and connection attributes.

To use Azure Active Directory authentication, you must configure your Azure SQL data source. For more information, see Configure and manage Azure AD authentication with Azure SQL.

Note

The ODBC Driver on Linux and macOS before version 17.6 only supports Azure Active Directory authentication directly against Azure Active Directory. If you are using Azure Active Directory username/password authentication from a Linux or macOS client and your Active Directory configuration requires the client to authenticate against an Active Directory Federation Services endpoint, authentication may fail. As of driver version 17.6, this limitation has been removed.

New and/or Modified DSN and Connection String Keywords

The Authentication keyword can be used when connecting with a DSN or connection string to control the authentication mode. The value set in the connection string overrides that in the DSN, if provided. The pre-attribute value of the Authentication setting is the value computed from the connection string and DSN values.

Name	Values	Default	Description
Authentication	(not set), (empty string), SqlPassword, ActiveDirectoryPassword, ActiveDirectoryIntegrated, ActiveDirectoryInteractive, ActiveDirectoryMsi, ActiveDirectoryServicePrincipal	(not set)	Controls the authentication mode. Value Description (not set) Authentication mode determined by other keywords (existing legacy connection options.) (empty string) (Connection string only.) Override and unset an Authentication value set in the DSN. SqlPassword Directly authenticate to a SQL Server instance using a username and password. ActiveDirectoryPassword Authenticate with an Azure Active Directory identity using a username and password. ActiveDirectoryIntegrated Windows, and Linux/Mac 17.6+, driver only. Authenticate with an Azure Active Directory identity using integrated authentication. ActiveDirectoryInteractive Windows driver only. Authenticate with an Azure Active Directory identity using interactive authentication. ActiveDirectoryMsi Authenticate with Azure Active Directory identity using managed identity authentication. For user-assigned identity, UID is set to the object ID of the user identity. ActiveDirectoryServicePrincipal (17.7+) Authenticate with Azure Active Directory identity using service principal authentication. UID is set to the client ID of the service principal. PWD is set to the client secret.
Encrypt	(not set), Yes/Mandatory(18.0+), No/Optional(18.0+), Strict(18.0+)	(see description)	Controls encryption for a connection. If the pre-attribute value of the Authentication setting isn't none in the DSN or connection string, the default is Yes. The default is also Yes in versions 18.0.1+. Otherwise, the default is No. If the attribute SQL_COPT_SS_AUTHENTICATION overrides the pre-attribute value of Authentication, explicitly set the value of Encryption in the DSN or connection string or connection attribute. The pre-attribute value of Encryption is Yes if the value is set to Yes in either the DSN or connection string.

New and/or Modified Connection Attributes

The following pre-connect connection attributes have either been introduced or modified to support Azure Active Directory authentication. When a connection attribute has a corresponding connection string or DSN keyword and is set, the connection attribute takes precedence.

Attribute	Type	Values	Default	Description
SQL_COPT_SS_AUTHENTICATION	SQL_IS_INTEGER	SQL_AU_NONE, SQL_AU_PASSWORD, SQL_AU_AD_INTEGRATED, SQL_AU_AD_PASSWORD, SQL_AU_AD_INTERACTIVE, SQL_AU_AD_MSI, SQL_AU_AD_SPA, SQL_AU_RESET	(not set)	See description of Authentication keyword above. SQL_AU_NONE is provided to explicitly override a set Authentication value in the DSN and/or connection string, while SQL_AU_RESET unsets the attribute if it was set, allowing the DSN or connection string value to take precedence.
SQL_COPT_SS_ACCESS_TOKEN	SQL_IS_POINTER	Pointer to ACCESSTOKEN or NULL	NULL	If non-null, specifies the AzureAD Access Token to use. It's an error to specify an access token and also UID, PWD, Trusted_Connection, or Authentication connection string keywords or their equivalent attributes. NOTE: ODBC Driver version 13.1 only supports this setting on Windows.
SQL_COPT_SS_ENCRYPT	SQL_IS_INTEGER	SQL_EN_OFF, SQL_EN_ON	(see description)	Controls encryption for a connection. SQL_EN_OFF and SQL_EN_ON disable and enable encryption, respectively. If the pre-attribute value of the Authentication setting isn't none or SQL_COPT_SS_ACCESS_TOKEN is set, and Encrypt wasn't specified in either the DSN or connection string, the default is SQL_EN_ON. Otherwise, the default is SQL_EN_OFF. If the connection attribute SQL_COPT_SS_AUTHENTICATION is set to not none, explicitly set SQL_COPT_SS_ENCRYPT to the desired value if Encrypt wasn't specified in the DSN or connection string. The effective value of this attribute controls whether encryption is used for the connection.
SQL_COPT_SS_OLDPWD	-	-	-	Not supported with Azure Active Directory, since password changes to Azure AD principals can't be accomplished through an ODBC connection. Password expiration for SQL Server Authentication was introduced in SQL Server 2005. The SQL_COPT_SS_OLDPWD attribute was added to allow the client to provide both the old and the new password for the connection. When this property is set, the provider won't use the connection pool for the first connection or for future connections, since the connection string contains the "old password", which has now changed.
SQL_COPT_SS_INTEGRATED_SECURITY	SQL_IS_INTEGER	SQL_IS_OFF,SQL_IS_ON	SQL_IS_OFF	Deprecated; use SQL_COPT_SS_AUTHENTICATION set to SQL_AU_AD_INTEGRATED instead. Forces use of Windows Authentication (Kerberos on Linux and macOS) for access validation on server login. When Windows Authentication is used, the driver ignores user identifier and password values provided as part of SQLConnect, SQLDriverConnect, or SQLBrowseConnect processing.

UI Additions for Azure Active Directory (Windows driver only)

The DSN setup and connection UIs of the driver have been enhanced with the more options necessary for using authentication with Azure AD.

Creating and editing DSNs in the UI

It's possible to use the new Azure AD authentication options when creating or editing an existing DSN using the driver's setup UI:

Authentication=ActiveDirectoryIntegrated for Azure Active Directory Integrated authentication to Azure SQL Database

Authentication=ActiveDirectoryPassword for Azure Active Directory username/password authentication to Azure SQL Database

Authentication=ActiveDirectoryInteractive for Azure Active Directory interactive authentication to Azure SQL Database

Note

As of driver version 17.9, the interactive authentication behavior has changed. Users will always be prompted for credentials unless the driver has a valid access token cached. This change prevents users on Azure Active Directory joined devices from skipping the prompt and automatically signing in with cached credentials when using ActiveDirectoryInteractive authentication.

Authentication=SqlPassword for username/password authentication to SQL Server (Azure or otherwise)

Trusted_Connection=Yes for Windows legacy SSPI-integrated authentication

Authentication=ActiveDirectoryMsi for Azure Active Directory Managed Identity authentication

Authentication=ActiveDirectoryServicePrincipal for Azure Active Directory service principal authentication

The seven options correspond to Trusted_Connection=Yes (existing legacy Windows SSPI-only integrated authentication) and Authentication= ActiveDirectoryIntegrated, SqlPassword, ActiveDirectoryPassword, ActiveDirectoryInteractive, ActiveDirectoryMsi, and ActiveDirectoryServicePrincipal respectively.

SQLDriverConnect Prompt (Windows driver only)

The prompt dialog displayed by SQLDriverConnect when it requests information required to complete the connection contains four new options for Azure AD authentication:

These options correspond to the same six available in the DSN setup UI above.

Example connection strings

1. SQL Server Authentication - legacy syntax. Server certificate isn't validated, and encryption is used only if the server enforces it. The username/password is passed in the connection string. server=Server;database=Database;UID=UserName;PWD=Password;Encrypt=no;TrustServerCertificate=yes;
2. SQL Authentication - new syntax. The client requests encryption (the default value of Encrypt is true) and the server certificate gets validated, whatever the encryption setting (unless TrustServerCertificate is set to true). The username/password is passed in the connection string. server=Server;database=Database;UID=UserName;PWD=Password;Authentication=SqlPassword;
3. Integrated Windows Authentication (Kerberos on Linux and macOS) using SSPI (to SQL Server or SQL IaaS) - current syntax. Server certificate isn't validated, unless encryption is required by the server. server=Server;database=Database;Trusted_Connection=yes;Encrypt=no;
4. (Windows driver only.) Integrated Windows Authentication using SSPI (if the target database is in SQL Server or SQL IaaS) - new syntax. The client requests encryption (the default value of Encrypt is true) and the server certificate gets validated, whatever the encryption setting (unless TrustServerCertificate is set to true). server=Server;database=Database;Authentication=ActiveDirectoryIntegrated;
5. Azure Active Directory Username/Password Authentication (if the target database is in Azure SQL Database). Server certificate gets validated, whatever the encryption setting (unless TrustServerCertificate is set to true). The username/password is passed in the connection string. server=Server;database=Database;UID=UserName;PWD=Password;Authentication=ActiveDirectoryPassword;Encrypt=yes;
6. (Windows, and Linux/macOS 17.6+, driver only.) Integrated Windows Authentication using ADAL or Kerberos, which involves redeeming Windows account credentials for an Azure AD-issued access token, assuming the target database is in Azure SQL Database. Server certificate gets validated, whatever the encryption setting (unless TrustServerCertificate is set to true). On Linux/macOS, a suitable Kerberos ticket needs to be available. For more information, see the section below on Federated Accounts and Using Integrated Authentication. server=Server;database=Database;Authentication=ActiveDirectoryIntegrated;Encrypt=yes;
7. (Windows driver only.) Azure AD Interactive Authentication uses Azure Active Directory Multi-Factor Authentication technology to set up connection. In this mode, by providing the login ID, an Azure Authentication dialog is triggered and allows the user to input the password to complete the connection. The username is passed in the connection string. server=Server;database=Database;UID=UserName;Authentication=ActiveDirectoryInteractive;Encrypt=yes;
8. Azure Active Directory Managed Identity Authentication uses system-assigned or user-assigned identity for authentication to set up connection. For user-assigned identity, UID is set to the object ID of the user identity.
   For system-assigned identity,
   server=Server;database=Database;Authentication=ActiveDirectoryMsi;Encrypt=yes;
   For user-assigned identity with object ID equals to myObjectId,
   server=Server;database=Database;UID=myObjectId;Authentication=ActiveDirectoryMsi;Encrypt=yes;
9. Azure Active Directory Service Principal Authentication server=Server;database=Database;UID=clientId;PWD=clientSecret;Authentication=ActiveDirectoryServicePrincipal;Encrypt=yes;

Note

• When using the Active Directory options with the Windows ODBC driver prior to version 17.4.2, ensure that the Active Directory Authentication Library for SQL Server has been installed. When using the Linux and macOS drivers, ensure that libcurl has been installed. For driver version 17.2 and later, this is not an explicit dependency since it is not required for the other authentication methods or ODBC operations.
• When Azure Active Directory configuration includes Conditional Access policies, and the client is Windows 10 or Server 2016 or later, authentication via Integrated or username/password may fail. Conditional Access policies require the use of Web Account Manager (WAM), which is supported in driver version 17.6 or later for Windows. To use WAM, create a new string or DWORD value named ADALuseWAM in HKLM\Software\ODBC\ODBCINST.INI\ODBC Driver 17 for SQL Server, HKCU\Software\ODBC\ODBC.INI\<your-user-DSN-name>, or HKLM\Software\ODBC\ODBC.INI\<your-system-DSN-name> for global, user DSN, or system DSN-scoped configuration respectively, and set it to a value of 1. Note that authentication with WAM does not support running the application as a different user with runas. Scenarios which require Conditional Access policies are not supported for Linux or macOS.
• To connect using a SQL Server account username and password, you may now use the new SqlPassword option, which is recommended especially for Azure SQL since this option enables more secure connection defaults.
• To connect using an Azure Active Directory account username and password, specify Authentication=ActiveDirectoryPassword in the connection string and the UID and PWD keywords with the username and password, respectively.
• To connect using Windows Integrated or Active Directory Integrated (Windows, and Linux/macOS 17.6+, driver only) authentication, specify Authentication=ActiveDirectoryIntegrated in the connection string. The driver will choose the correct authentication mode automatically. For driver versions 17.7 or earlier, UID and PWD must not be specified. Beginning with driver version 17.8, UID and PWD are ignored.
• To connect using Active Directory Interactive (Windows driver only) authentication, UID must be specified. For driver versions 17.7 and earlier, PWD must not be specified. Beginning with driver version 17.8, PWD is ignored.
• Starting with version 18.1, Trusted_Connection=Yes no longer uses Azure Active Directory federated authentication by default and uses SSPI-integrated instead. To use Azure Active Directory for this option, TrustedConnection_UseAAD=Yes should be configured.
• ODBC driver versions 17.7 and lower have a known issue with connection timeout when AAD authentication and Force Encryption are enabled on a SQL instance. SQL Server errorlog may contain error messages such as: "Error: 33155, Severity: 20, State: 1. A disconnect event was raised when server is waiting for Federated Authentication token. This could be due to client close or server timeout expired.". If you are using SQL high availability solutions such as Availability Groups or Failover Cluster Instances, the internal cluster communication for SQL may be affected by this behavior which can affect resource availability. In the cluster log, you may see error messages such as: [hadrag] Connect to SQL Server ...ODBC Error: [HY000] [Microsoft][ODBC Driver 17 for SQL Server]An unknown error has occurred. Detailed error information is not available. (0). ODBC driver versions 17.10 and higher fix this issue and with SQL Server 2022 GDR KB5021522 /CU1 KB5022375, the latest driver which contains this fix is installed with SQL installation. You can verify which version of ODBC driver you have installed by referring to the ODBC Data Source Administrator.

Authenticating with an Access Token

The SQL_COPT_SS_ACCESS_TOKEN pre-connection attribute allows the use of an access token obtained from Azure AD for authentication instead of username and password, and also bypasses the negotiation and obtaining of an access token by the driver. To use an access token, set the SQL_COPT_SS_ACCESS_TOKEN connection attribute to a pointer to an ACCESSTOKEN structure:

typedef struct AccessToken
{
    DWORD dataSize;
    BYTE data[];
} ACCESSTOKEN;

The ACCESSTOKEN is a variable-length structure consisting of a 4-byte length followed by length bytes of opaque data that form the access token. Because of how SQL Server handles access tokens, one obtained via an OAuth 2.0 JSON response must be expanded so that each byte is followed by a zero padding byte, similar to a UCS-2 string containing only ASCII characters. However, the token is an opaque value and the length specified, in bytes, must NOT include any null terminator. Because of their considerable length and format constraints, this method of authentication is only available programmatically via the SQL_COPT_SS_ACCESS_TOKEN connection attribute. There's no corresponding DSN or connection string keyword. The connection string must not contain UID, PWD, Authentication, or Trusted_Connection keywords.

Note

The ODBC Driver version 13.1 only supports this authentication on Windows. Subsequent versions support this authentication on all platforms.

Azure Active Directory Authentication Sample Code

The following sample shows the code required to connect to SQL Server using Azure Active Directory with connection keywords. There's no need to change the application code itself. The connection string, or DSN if one is used, is the only modification needed to use Azure AD for authentication:

    ...
    SQLCHAR connString[] = "Driver={ODBC Driver 18 for SQL Server};Server={server};UID=myuser;PWD=myPass;Authentication=ActiveDirectoryPassword;Encrypt=yes;"
    ...
    SQLDriverConnect(hDbc, NULL, connString, SQL_NTS, NULL, 0, NULL, SQL_DRIVER_NOPROMPT);
    ...

The following sample shows the code required to connect to SQL Server using Azure Active Directory with access token authentication. In this case, it's necessary to modify application code to process the access token and set the associated connection attribute.

    SQLCHAR connString[] = "Driver={ODBC Driver 18 for SQL Server};Server={server};Encrypt=yes;"
    SQLCHAR accessToken[] = "eyJ0eXAiOi..."; // In the format extracted from an OAuth JSON response
    ...
    DWORD dataSize = 2 * strlen(accessToken);
    ACCESSTOKEN *pAccToken = malloc(sizeof(ACCESSTOKEN) + dataSize);
    pAccToken->dataSize = dataSize;
    // Expand access token with padding bytes
    for(int i = 0, j = 0; i < dataSize; i += 2, j++) {
        pAccToken->data[i] = accessToken[j];
        pAccToken->data[i+1] = 0;
    }
    ...
    SQLSetConnectAttr(hDbc, SQL_COPT_SS_ACCESS_TOKEN, (SQLPOINTER)pAccToken, SQL_IS_POINTER);
    SQLDriverConnect(hDbc, NULL, connString, SQL_NTS, NULL, 0, NULL, SQL_DRIVER_NOPROMPT);
    ...
    free(pAccToken);

The following sample connection string is for use with Azure Active Directory Interactive Authentication. It doesn't contain PWD field as the password would be entered on the Azure Authentication screen.

SQLCHAR connString[] = "Driver={ODBC Driver 18 for SQL Server};Server={server};UID=myuser;Authentication=ActiveDirectoryInteractive;Encrypt=yes;"

The following sample connection string is for use with Azure Active Directory Managed Identity Authentication. UID is set to the object ID of the user identity when using a user-assigned identity.

// For system-assigned identity,
SQLCHAR connString[] = "Driver={ODBC Driver 18 for SQL Server};Server={server};Authentication=ActiveDirectoryMsi;Encrypt=yes;"
...
// For user-assigned identity with object ID equals to myObjectId
SQLCHAR connString[] = "Driver={ODBC Driver 18 for SQL Server};Server={server};UID=myObjectId;Authentication=ActiveDirectoryMsi;Encrypt=yes;"

Considerations for using ADFS Federated Accounts on Linux/macOS

Starting with version 17.6, the drivers for Linux and macOS support authentication using Azure Active Directory ADFS-federated accounts using either username/password (ActiveDirectoryPassword) or Kerberos (ActiveDirectoryIntegrated). There are some limitations dependent on the platform when using Integrated mode.

When authenticating with a user whose UPN suffix is different from the Kerberos realm, that is, an alternate UPN suffix is in use, it's necessary to use the Enterprise Principal option (use the -E option with kinit, and supply the principal name in the form user@federated-domain) when obtaining Kerberos tickets. This way, the driver can correctly determine both the federated domain and the Kerberos realm.

You can verify that a suitable Kerberos ticket is available by inspecting the output of the klist command. If the federated domain is the same as the Kerberos realm and UPN suffix, the principal name is of the form user@realm. If it's different, the principal name should be of the form user@federated-domain@realm.

Linux

On SuSE 11, the default Kerberos library version of 1.6.x doesn't support the Enterprise Principal option necessary to use alternate UPN suffixes. To use alternate UPN suffixes with Azure AD Integrated authentication, upgrade the Kerberos library to 1.7 or newer.

On Alpine Linux, the default libcurl doesn't support the SPNEGO/Kerberos authentication required for Azure AD Integrated authentication.

macOS

The system Kerberos library kinit supports Enterprise Principal with the --enterprise option, but also implicitly does name canonicalization, which prevents the use of alternate UPN suffixes. To use alternate UPN suffixes with Azure AD Integrated authentication, install a newer Kerberos library via brew install krb5 and use its kinit with the -E option as described above.

See Also

Token-based authentication support for Azure SQL Database using Azure AD auth
Using Integrated Authentication