When we use external data connections then the data connection file talks with the excel services by means of authentication. These authentications are of three types:
1. Windows
2. None
3. SSO
In Windows authentication mode, Excel Services attempts to use the Windows identity of the user who is logged on when authenticating with the external data source.
In SSO option, The SSO service uses a centralized database to store authentication credentials. Excel Services uses the SSO application ID that is specified for the data connection to request the credentials when authenticating with the data source.
Now the options remains is NONE-Selecting None for the authentication mode in the Excel Services Authentication Settings dialog box causes Excel Services to assume that the connection string contains the user name and password needed to authenticate with the data source. If the connection string requires the use of integrated security, the Excel Services Unattended Account is used for authentication.
To use the None option, we need to have:
Configured the Unattended Account. Excel Services impersonates the Unattended Account when it tries to authenticate with a data source by using either no authentication setting (None), or single sign-on (SSO) when the SSO application is not storing Windows account credentials.
Where is this unattended account we need to specify?
Central Administration
Shared Service provider (SSP
Excel service settings
Unattended account.
Here is the screenshot regarding this:
If you have any queries / questions regarding the above mentioned information then please let me know.
I would be more than happy to help you as well as resolves your issues, Thank you
