asp.net - How can I fix the Kerberos double-hop issue?

Question

I'm having some trouble calling a web service from within a web application and I was hoping someone here might be able to help. From what I can tell, this seems to have something to do with the Kerberos double-hop issue. However, if it is, I'm not sure what to do to actually fix the problem. To make things harder, I don't have the proper permissions to make changes to Active Directory accounts, so I need to know what to ask for when requesting changes. In my situation, I need to pass the credentials (Integrated Windows Authentication) from a web application onto a backend web service so that the web service runs under the proper user context.

Here's my exact issue:

This works

This doesn't work

The only difference between the working scenario and the non-working scenario is that the working scenario is running the application on localhost (whether a developer's PC or on the server in question) and the non-working example is running on another machine. The code between both scenarios is exactly the same.

What I've tried

1. Adding an SPN to the domain account that runs the app pool for each server setspn -a http/server1 DOMAINaccount
2. Different methods of impersonation
3. Removing the impersonation code using(...) and executing the web service call as the app pool account. This works as expected.

Does anyone have any idea on what I might be able to do in order to fix this problem?

Answer 1

The intermediate server must be trusted for delegation. Otherwise no credential will be delegated and the intermediate server cannot impersonate the original client.