You can use the SQL Server Adapter to connect to any instance of Microsoft SQL Server, Azure SQL Server, or Azure Data Warehouse.

Connecting to to Microsoft SQL Server

Specify the following connection properties to connect to SQL Server:

• Server: The name of the server running SQL Server.
• Database: The name of the SQL Server database.

Authenticating to SQL Server

The adapter supports authenticating to SQL Server using SQL Server authentication or Kerberos authentication.

SQL Server Authentication

To authenticate to Microsoft SQL Server using your SQL Server user login credentials, set the following:

• AuthScheme: Set this to Password.
• User: The username provided for authentication with SQL Server.
• Password: The password associated with the authenticating user.

Kerberos

To authenticate to SQL Server with Kerberos, set AuthScheme to KERBEROS.

Authenticating to SQL Server via Kerberos requires you to define authentication properties and to choose how Kerberos should retrieve authentication tickets.

Retrieve Kerberos Tickets

Kerberos tickets are used to authenticate the requester's identity. The use of tickets instead of formal logins/passwords eliminates the need to store passwords locally or send them over a network. Users are reauthenticated (tickets are refreshed) whenever they log in at their local computer or enter kinit USER at the command prompt.

The adapter provides three ways to retrieve the required Kerberos ticket, depending on whether or not the KRB5CCNAME and/or KerberosKeytabFile variables exist in your environment.

MIT Kerberos Credential Cache File

This option enables you to use the MIT Kerberos Ticket Manager or kinit command to get tickets. With this option there is no need to set the User or Password connection properties.

This option requires that KRB5CCNAME has been created in your system.

To enable ticket retrieval via MIT Cerberos Credential Cache Files:

1. Ensure that the KRB5CCNAME variable is present in your environment.
2. Set KRB5CCNAME to a path that points to your credential cache file. (For example, C:\krb_cache\krb5cc_0 or /tmp/krb5cc_0.) The credential cache file is created when you use the MIT Kerberos Ticket Manager to generate your ticket.
3. To obtain a ticket:
   1. Open the MIT Kerberos Ticket Manager application.
   2. Click Get Ticket.
   3. Enter your principal name and password.
   4. Click OK.

   If the ticket is successfully obtained, the ticket information appears in Kerberos Ticket Manager and is stored in the credential cache file.

The adapter uses the cache file to obtain the Kerberos ticket to connect to SQL Server.

Note: If you would prefer not to edit KRB5CCNAME, you can use the KerberosTicketCache property to set the file path manually. After this is set, the adapter uses the specified cache file to obtain the Kerberos ticket to connect to SQL Server.

Keytab File

If your environment lacks the KRB5CCNAME environment variable, you can retrieve a Kerberos ticket using a Keytab File.

To use this method, set the User property to the desired username, and set the KerberosKeytabFile property to a file path pointing to the keytab file associated with the user.

User and Password

If your environment lacks the KRB5CCNAME environment variable and the KerberosKeytabFile property has not been set, you can retrieve a ticket using a user and password combination.

To use this method, set the User and Password properties to the user/password combination that you use to authenticate with SQL Server.

Enabling Cross-Realm Authentication

More complex Kerberos environments can require cross-realm authentication where multiple realms and KDC servers are used. For example, they might use one realm/KDC for user authentication, and another realm/KDC for obtaining the service ticket.

To enable this kind of cross-realm authentication, set the KerberosRealm and KerberosKDC properties to the values required for user authentication. Also, set the KerberosServiceRealm and KerberosServiceKDC properties to the values required to obtain the service ticket.

Connecting to Azure SQL Server and Azure Data Warehouse

You can connect to Azure SQL Server or Azure Data Warehouse by setting the following connection properties:

• Server: The server running Azure. You can find this by logging into the Azure portal and navigating to SQL databases (or SQL data warehouses) -> Select your database -> Overview -> Server name.
• Database: The name of the database, as seen in the Azure portal on the SQL databases (or SQL warehouses) page.

Azure

Standard credentials may be used to authenticate to an Azure-hosted SQL Server. To do so, set the following:

• AuthScheme: Password (SQL Server credentials) or NTLM (Windows Credentials).
• User: The name of the user authenticating to Azure.
• Password: The password associated with the authenticating user.

Alternatively, a form of OAuth may be used by setting AuthScheme to one of AzureAd, AzurePassword, or AzureMSI. All OAuth connections require setting Tenant:

• AzureTenant: The id of the tenant the SQL Server database is hosted on.

AzureAD

Azure AD

Azure AD is Microsoft’s multi-tenant, cloud-based directory and identity management service. It is user-based authentication that requires that you set AuthScheme to AzureAD.

Desktop Applications

CData provides an embedded OAuth application that simplifies authentication at the desktop.

Before you connect, set the following variables:

• InitiateOAuth: GETANDREFRESH. Used to automatically get and refresh the OAuthAccessToken. CData provides an embedded OAuth application that simplifies authentication at the desktop; that is, in situations where the user is using a local server not connected to the internet.

  You can also authenticate from the desktop via a custom OAuth application, which you configure and register at the SQL Server console. For further information, see Creating a Custom Azure AD Application.

• Custom Azure AD applications only:
  • OAuthClientId: The client Id assigned when you registered your custom OAuth application.
  • OAuthClientSecret: The client secret assigned when you registered your custom OAuth application.
  • CallbackURL: The redirect URI defined when you registered your custom OAuth application.

When you connect, the adapter opens the SQL Server's OAuth endpoint in your default browser. Log in and grant permissions to the application. The adapter then completes the OAuth process:

1. Extracts the access token from the callback URL and authenticates requests.
2. Obtains a new access token when the old one expires.
3. Saves OAuth values in OAuthSettingsLocation. These values persist across connections.

When the access token expires, the adapter refreshes it automatically.

Web Applications

Authenticating via the Web requires you to create and register a custom OAuth application with SQL Server, as described in Creating a Custom Azure AD Application. You can then use the adapter to get and manage the OAuth token values.

This section describes how to get the OAuth access token, how to have the driver refresh the OAuth access token automatically, and how to refresh the OAuth access token manually.

Get the OAuth access token:

1. To obtain the OAuthAccessToken, set these connection properties:
   • For authentication using a Client Secret:
     • OAuthClientId: The client Id in your application settings.
     • OAuthClientSecret: The client secret in your application settings.
   • For authentication using a Certificate:
     • OAuthClientId: The client Id in your application settings.
     • OAuthJWTCert: The JWT Certificate store.
     • OAuthJWTCertType: The type of the certificate store specified by OAuthJWTCert.
2. Call stored procedures to complete the OAuth exchange:
   • Call the GetOAuthAuthorizationUrl stored procedure. Set the AuthMode input to WEB and the CallbackURL to the Redirect URI you specified in your application settings. The stored procedure returns the URL to the OAuth endpoint.
   • Navigate to the URL that the stored procedure returned in Step 1. Log in and authorize the web application. You are redirected back to the callback URL.
   • Call the GetOAuthAccessToken stored procedure. Set the AuthMode input to WEB. Set the Verifier input to the code parameter in the query string of the redirect URI.

After you obtain the access and refresh tokens, you can connect to data and refresh the OAuth access token automatically.

Automatic refresh of the OAuth access token:

To have the adapter automatically refresh the OAuth access token, do the following:

1. The first time you connect to data, set these connection parameters:
   • InitiateOAuth: REFRESH.
   • OAuthClientId: The client Id in your custom OAuth application settings.
   • OAuthClientSecret: The client secret in your custom OAuth application settings.
   • OAuthAccessToken: The access token returned by GetOAuthAccessToken.
   • OAuthSettingsLocation: The path where you want the adapter to save the OAuth values, which persist across connections.
2. On subsequent data connections, set:
   • InitiateOAuth
   • OAuthSettingsLocation

Manual refresh of the OAuth access token:

The only value needed to manually refresh the OAUth access token is the OAuth refresh token.

1. To manually refresh the OAuthAccessToken after the ExpiresIn period (returned by GetOAuthAccessToken) has elapsed, call the RefreshOAuthAccessToken stored procedure.
2. Set these connection properties:
   • OAuthClientId: The Client Id in your custom OAuth application settings.
   • OAuthClientSecret: The Client Secret in your custom OAuth application settings.

3. Call RefreshOAuthAccessToken with OAuthRefreshToken set to the OAuth refresh token returned by GetOAuthAccessToken.
4. After the new tokens have been retrieved, set the OAuthAccessToken property to the value returned by RefreshOAuthAccessToken. This opens a new connection.

Store the OAuth refresh token so that you can use it to manually refresh the OAuth access token after it has expired.

Headless Machines

If you need to log in to a resource that resides on a headless machine, you must authenticate on another device that has an internet browser. You can do this in either of the following ways:

• Obtain the OAuthVerifier value as described in Obtain and Exchange a Verifier Code, below.
• Install the adapter on another machine and transfer the OAuth authentication values after you authenticate through the usual browser-based flow.

After you execute either of these options, configure the driver to automatically refresh the access token on the headless machine.

Obtaining and Exchanging a Verifier Code

To obtain a verifier code, you must authenticate at the OAuth authorization URL from a machine with an internet browser, and obtain the OAuthVerifier connection property.

1. Choose one of these options:
   • If you are using the Embedded OAuth Application, click SQL Server OAuth endpoint to open the endpoint in your browser.
   • If you are using a custom OAuth application, set the following properties to create the Authorization URL:
     • InitiateOAuth: OFF.
     • OAuthClientId: The client Id assigned when you registered your application.
     • OAuthClientSecret: The client secret assigned when you registered your application.
     After the Authorization URL is established, call the GetOAuthAuthorizationUrl stored procedure with the appropriate CallbackURL. Open the URL returned by the stored procedure in a browser.

2. Log in and grant permissions to the adapter. You are redirected to the callback URL, which contains the verifier code.
3. Save the value of the verifier code. Later you will set this in the OAuthVerifier connection property.

Next, exchange the OAuth verifier code for OAuth refresh and access tokens.

To obtain the OAuth authentication values, set these properties:

• InitiateOAuth: REFRESH.
• OAuthVerifier: The verifier code.
• OAuthSettingsLocation: The location of the file where the driver saves the OAuth token values that persist across connections.
• Custom applications only:
  • OAuthClientId: (custom applications only) Set this to the client Id in your custom OAuth application settings.
  • OAuthClientSecret: (custom applications only) Set this to the client secret in the custom OAuth application settings.

After the OAuth settings file is generated, re-set the following properties to connect:

• InitiateOAuth: REFRESH.
• OAuthSettingsLocation: The location containing the encrypted OAuth authentication values. Make sure this location grants read and write permissions to the adapter to enable the automatic refreshing of the access token.
• Custom applications only:
  • OAuthClientId: The client Id assigned when you registered your application.
  • OAuthClientSecret: The client secret assigned when you registered your application.

Transferring OAuth Settings

Prior to connecting on a headless machine, you must create and install a connection with the driver on a device that supports an internet browser. Set the connection properties as described in "Desktop Applications" above.

After completing the instructions in "Desktop Applications", the resulting authentication values are encrypted and written to the location specified by OAuthSettingsLocation. The default filename is OAuthSettings.txt.

Once you have successfully tested the connection, copy the OAuth settings file to your headless machine.

On the headless machine, set the following connection properties to connect to data:

• InitiateOAuth: REFRESH.
• OAuthSettingsLocation: The location of your OAuth settings file. Make sure this location gives read and write permissions to the adapter to enable the automatic refreshing of the access token.
• Custom applications only:
  • OAuthClientId: The client Id assigned when you registered your application.
  • OAuthClientSecret: The client secret assigned when you registered your application.

Azure Service Principal

Azure Service Principal is role-based application-based authentication. This means that authentication is done per application, rather than per user. All tasks taken by the app are done without a default user context, but based on the assigned roles. The application access to the resources is controlled through the assigned roles' permissions.

To use Azure Service Principal authentication, you must:

• Set up the ability to assign a role to the authentication application. To do this, create a custom OAuth AD application, as described in Creating a Custom Azure AD Application.
• Register an application with an Azure AD tenant, to create a new service principal that can be used with the role-based access control, to access resources in your subscription.

Do the following:

1. Create a custom Azure AD application, as described in Creating a Custom Azure AD Application.
2. Assign a role to the application:
   1. Use the search bar to search for the Subscriptions service.
   2. Open the Subscriptions page.
   3. Select the subscription to which to assign the application.
   4. Open the Access control (IAM).
   5. Select Add > Add role assignment. SQL Server opens the Add role assignment page.
   6. Assign your custom Azure AD application the role of Owner.

Client Credentials

Client credentials refers to a flow in OAuth where there is no direct user authentication taking place. Instead, credentials are created for just the application itself. All tasks taken by the application are done without a default user context. This makes the authentication flow a bit different from the standard flow.

All permissions related to the client OAuth flow require admin consent. This means you cannot use the application embedded with the SQL Server Adapter in the client OAuth flow. You must create your own OAuth application to use client credentials. See Creating a Custom Azure AD Application for more information.

In your App Registration in portal.azure.com, navigate to API Permissions and select the Microsoft Graph permissions. There are two distinct sets of permissions: Delegated permissions and Application permissions. The permissions used during client credential authentication are under "Application Permissions".

Select the permissions you require for your integration. After you do this, set the following connection properties:

• AuthScheme: AzureServicePrincipal.
• InitiateOAuth: GETANDREFRESH. You can use InitiateOAuth to avoid repeating the OAuth exchange and manually setting the OAuthAccessToken.
• AzureTenant: The tenant you wish to connect to.
• OAuthGrantType: CLIENT.
• OAuthClientId: The client Id in your application settings.
• OAuthClientSecret: The client secret in your application settings.

Authentication with client credentials takes place automatically like any other connection, except there is no window opened prompting the user. Because there is no user context, there is no need for a browser popup. Connections will take place and be handled internally.

Auth Certificate

Auth Certificate refers to an OAuth flow that uses a certificate to enable server-to-server authentication. All permissions related to the client OAuth flow require admin consent. This means you cannot use the application embedded with the SQL Server Adapter in the client OAuth flow. You must create your own OAuth application to use an OAuth certificate. See Creating a Custom Azure AD Application for more information.

In your App Registration in portal.azure.com, navigate to API Permissions and select the client Graph permissions. There are two distinct sets of permissions: Delegated permissions and Application permissions. The permissions used during certificate authentication are under "Application Permissions".

Select the permissions that apply to your particular integration. After you do this, set the following connection properties:

• AuthScheme: AzureServicePrincipalCert.
• AzureTenant: The tenant to which you need to connect.
• OAuthJWTCert: The JWT Certificate store.
• OAuthJWTIssuer: The OAuth client Id.
• OAuthJWTCertType: The type of the certificate store specified by OAuthJWTCert.

Certificate authentication takes place automatically. Since there is no user context, there is no pop-up to signal the point at which authentication occurs. Connections are made and handled internally.

Azure Password

Set AuthScheme to AzurePassword.

To connect using your Azure credentials directly, specify the following connection properties:

• User: Set this to the user account you use to connect to Azure.
• Password: Set this to the password you use to connect to Azure.
• AzureTenant: Set this to the Directory (tenant) ID, found on the Overview page of the OAuth app used to authenticate to SQL Server on Azure.

Managed Service Identity (MSI)

If you are running SQL Server on an Azure VM and want to leverage MSI to connect, set AuthScheme to AzureMSI.

User-Managed Identities

To obtain a token for a managed identity, use the OAuthClientId property to specify the managed identity's "client_id".

When your VM has multiple user-assigned managed identities, you must also specify OAuthClientId.