Windows authentication from ASP.NET to SQL Server

[Nils Magnus Englund]

Hello,

I am having trouble using Integrated Windows Authentication between our
intranet server and our database server, both of which are on our local
domain.

Windows authentication works for our intranet server - my domain user
"DOM\nme" is correctly authenticated and authorized to view the ASP.NET page
on our intranet. The ASP.NET application uses impersonation (<identity
impersonate="true"> in Web.config).

Windows authentication also works for the SQL Server; when logged on to the
domain, I can start Query Analyzer and connect to the SQL Server using
Windows authentication. Permissions on the SQL Server are also correctly set
up.

However, problems arise when I want to connect to the SQL Server from the
ASP.NET page - I get the fairly common error message below:

Login failed for user '(null)'. Reason: Not associated with a trusted SQL
Server connection.

Although I do get a lot of hits when searching for this specific error, I
still can't seem to find the cause of the problem.

The connection string I'm using to connect to the SQL Server is:
"Server=DB;Integrated Security=SSPI;Database=IntranetDB".

When setting <identity impersonate="false">, I get the error message "Login
failed for user 'DOM\INTRANET$'." - DOM\INTRANET$ is the hostname of the
intranet server.

In the database servers event log, I can see two events (supplied below)
after trying to authenticate (unsuccessfully) from the ASP.NET application
to the SQL Server as "DOM\nme".

What do I need to do to let users use Windows authentication against the DB
server as well?


Regards,
Nils Magnus Englund


(event log entries follows...)


Date: 08.08.2005
Source: Security
Time: 15:14:55
Category: Logon/Logoff
Type: Success Audit
Event ID: 540
User: NT AUTHORITY\ANONYMOUS LOGON
Computer: DB

Description:
Successful Network Logon:
User Name:
Domain:
Logon ID: (0x0,0x5CE408)
Logon Type: 3
Logon Process: NtLmSsp
Authentication Package: NTLM
Workstation Name: INTRANET
Logon GUID: -
Caller User Name: -
Caller Domain: -
Caller Logon ID: -
Caller Process ID: -
Transited Services: -
Source Network Address: -
Source Port: -


Date: 08.08.2005
Source: Security
Time: 15:14:55
Category: Logon/Logoff
Type: Success Audit
Event ID: 538
User: NT AUTHORITY\ANONYMOUS LOGON
Computer: DB

Description:
User Logoff:
User Name: ANONYMOUS LOGON
Domain: NT AUTHORITY
Logon ID: (0x0,0x5CE408)
Logon Type: 3

 

[Guest]

The easiest way is to turn off anonymous access for the Intranet site. This
will force authentication, usually through a login box (although the network
admins can alleviate this through policy).

--
Gregory A. Beamer
MVP; MCP: +I, SE, SD, DBA

***************************
Think Outside the Box!
***************************

 

[Stefan]

Do you have anonymous authentication disabled in IIS?
If so, do you have <authentication mode="Windows" /> set in your
web.config?

 

[Nils Magnus Englund]

Do you have anonymous authentication disabled in IIS?
If so, do you have <authentication mode="Windows" /> set in your
web.config?

In reply to both Stefan and Gregory;

Anonymous authentication is disabled, and I have authentication mode
"Windows" set in Web.config.

Again, let me specify that the Windows authentication for the ASP.NET page
works, and the User.Identity part successfully retrieves the domain user.
It's the Windows authentication to the SQL Server from the ASP.NET page that
causes trouble.


Regards,
Nils Magnus Englund

 

[Patrick.O.Ige]

Nils hae you give your database and table the ASPNET account permission?
Try doing that.
Patrick

 

[Nils Magnus Englund]

Hi Patrick,

Since the database server isn't the same server as the ASP.NET server, and
since ASPNET is a local user, I cannot use that user to set permissions on
the database server. However, because of the identity impersonation, is the
application supposed to be connecting as ASPNET at all?


Regards,
Nils Magnus Englund

 

[Paul Clement]

¤ Hi Patrick,
¤
¤ Since the database server isn't the same server as the ASP.NET server, and
¤ since ASPNET is a local user, I cannot use that user to set permissions on
¤ the database server. However, because of the identity impersonation, is the
¤ application supposed to be connecting as ASPNET at all?
¤

If your ASP.NET app is configured for Integrated Windows security, credentials cannot be delegated
by IIS to the remote database server w/o implementing Kerberos.

The reason for this is that NTLM authenticates credentials under IIS Integrated Windows security so
IIS never receives the credentials and cannot forward them for delegation.


Paul
~~~~
Microsoft MVP (Visual Basic)

 

[Nils Magnus Englund]

If your ASP.NET app is configured for Integrated Windows security,

credentials cannot be delegated
by IIS to the remote database server w/o implementing Kerberos.

The reason for this is that NTLM authenticates credentials under IIS
Integrated Windows security so
IIS never receives the credentials and cannot forward them for delegation.

But why can't I use Kerberos authentication? Is it anyway to force the
application to use Kerberos? The WindowsIdentity.AuthenticationType property
returns "Negotiate" - this should be "Kerberos", should it not?


Regards,
Nils Magnus Englund

 

[Paul Clement]

¤ > If your ASP.NET app is configured for Integrated Windows security,
¤ > credentials cannot be delegated
¤ > by IIS to the remote database server w/o implementing Kerberos.
¤ >
¤ > The reason for this is that NTLM authenticates credentials under IIS
¤ > Integrated Windows security so
¤ > IIS never receives the credentials and cannot forward them for delegation.
¤
¤
¤ But why can't I use Kerberos authentication? Is it anyway to force the
¤ application to use Kerberos? The WindowsIdentity.AuthenticationType property
¤ returns "Negotiate" - this should be "Kerberos", should it not?
¤

You can use Kerberos, but your environment must be configured for it. The following should help:

http://msdn.microsoft.com/library/d...y/en-us/vsent7/html/vxconaspnetdelegation.asp
http://msdn.microsoft.com/library/default.asp?url=/library/en-us/dnnetsec/html/SecNetHT05.asp


Paul
~~~~
Microsoft MVP (Visual Basic)