Using DefaultCredentials and DefaultNetworkCredentials

Question

We're having a hard time figuring how these credentials objects work. In fact, they may not work how we expected them to work. Here's an explanation of the current issue.

We got 2 servers that needs to talk with each other through webservices. The first one (let's call it Server01) has a Windows Service running as the NetworkService account. The other one Server02 has ReportingServices running with IIS 6.0. The Windows Service on Server01 is trying to use the Server02 ReportingServices WebService to generate reports and send them by email.

So, here's what we tried so far.

Setting the credentials at runtime (This works perfectly fine):

 rs.Credentials = new NetworkCredentials("user", "pass", "domain");

Now, if we could use a generic user all would be fine, however... we are not allowed to. So, we are trying to use the DefaultCredetials or DefaultNetworkCredentials and pass it to the RS Webservice:

rs.Credentials = System.Net.CredentialCache.DefaultNetworkCredentials

Or:

rs.Credentials = System.Net.CredentialCache.DefaultCredentials

Either way won't work. We're always getting 401 Unauthrorized from IIS. Now, what we know is that if we want to give access to a resource logged as NetworkService, we need to grant it to DOMAIN\MachineName$ (http://msdn.microsoft.com/en-us/library/ms998320.aspx):

Granting Access to a Remote SQL Server

If you are accessing a database on another server in the same domain (or in a trusted domain), the Network Service account's network credentials are used to authenticate to the database. The Network Service account's credentials are of the form DomainName\AspNetServer$, where DomainName is the domain of the ASP.NET server and AspNetServer is your Web server name.

For example, if your ASP.NET application runs on a server named SVR1 in the domain CONTOSO, the SQL Server sees a database access request from CONTOSO\SVR1$.

We assumed that granting access the same way with IIS would work. However, it does not. Or at least, something is not set properly for it to authenticate correctly.

So, here are some questions:

1. We've read about "Impersonating Users" somewhere, do we need to set this somewhere in the Windows Service ?

2. Is it possible to grant access to the NetworkService built-in account to a remote IIS server ?

Thanks for reading!

Answer 1

All details you need are included in this very old article,

http://msdn.microsoft.com/en-us/library/ms998351.aspx

In short, when you find it confusing to troubleshoot issues like this, you should first review the technical details behind ASP.NET impersonation carefully.