Menu
I'm trying to use Impersonation and Delegation in an intranet ASP.Net web-app in order to pass authenticated users' credentials onto a SQL Server.
The web server and SQL server are two separate machines, but in the same domain, so Delegation is required.
I've done the following:
<authentication mode="Windows"/> and <identity impersonate="true"/> in my web-app's web.config.Apparently this should all work, but it doesn't (the SQL Server is denying access to the anonymous user - "Login failed for user 'NT AUTHORITY\ANONYMOUS LOGON'").
In IIS7, the Application Pool is set to use Integrated Pipleline Mode and is running with the NetworkService Identity. The website only has Windows Authentication enabled, Extended Protection is Off, Kernel-mode authentication is enabled, and NTLM is the provider.
All the web pages I've read seem to indicate that my setup should work. What am I missing?
650
When using impersonation, ASP.NET applications can execute with the Windows identity (user account) of the user making the request. Impersonation is commonly used in applications that rely on Microsoft Internet Information Services (IIS) to authenticate the user. ASP.NET impersonation is disabled by default.
In the application's Web. config file, set the impersonate attribute in the identity element to true. Set the NTFS access control list (ACL) for the ManagerInformation directory to allow access to only those identities that are in the Windows Manager group and any required system accounts.
Scott Stauffer. Kerberos delegation is a method of securely transferring a user's credentials from the client's PC to the middle application tier such as a web server, then on to a back-end database tier.
Impersonation is the process of executing code in the context of another user identity. By default, all ASP.NET code is executed using a fixed machine-specific account. To execute code using another identity we can use the built-in impersonation capabilities of ASP.NET.
I've discovered the answer:
The Windows Authentication provider in IIS7 must be set to Negotiate:Kerberos, not NTLM. This means that the Kernel-mode authentication setting must be disabled. This seems to be fine. I think I'm right in saying that Kernel-mode authentication is required when using a custom identity, i.e. one specific identity. Delegation can use an arbitrary number of identities. So all is well.
I've written a blog post about this too, which goes into a bit more detail.
197
If you love us? You can donate to us via Paypal or buy me a coffee so we can maintain and grow! Thank you!
Donate Us With
