IIS and ASP.NET 2.0.50727.0 Issues with SharePoint

There are two main reasons I can think of:

NTLM double-hop issue

This is probably the problem. Are you:

• Using Windows authentication (NTLM) in your network and not Kerberos?
• Using impersonation to connect to the databases? (True if your database connection string contains Integrated Security=SSPI or Trusted_Connection=True)

Then you are probably facing the double hop problem. This occurs because ASP.NET passes your Windows credentials to only one server, not two. So it will go from your local PC to the SharePoint server, but not be passed on to the database server.

The only way I know of to avoid this (unless you want to configure Kerberos) is set up a SQL account and use that in your connection string to the database.

Permissions to resources

The web part is accessing resources that your local PC account does not have permission to access.

Perform some sort of logging around the parts of your web part that you believe are causing the problem and narrow this down to a particular line of code. Note that while this may be a database authentication problem, it could also be that the web part is accessing some CSS file or other resource that your local account doesn't have permission to access.

Without much work this is not possible if the server and client computers aren't in the same domain.

In a domain environment, authenticating for Sharepoint access the process in the background works roughly like this:

• First you authenticate to domain controller
• Domain controller assigns you a ticket
• Web server checks your ticket

In non domain environment it is simply not trivial to configure such automatic authentication on a Serverside.

Workaround

You can configure automatic authentication on the client side by storing password in the browser or by configuring IE to authenticate with current user credentials.

Firefox: When navigating to Sharepoint site new dialog box opens up, asking for credentials. After you supply the credentials, a "dialog-line" appears at the top of Firefox browsing area, asking if user wants to store password. By selecting OK, credentials get stored. Next time visiting a site user simply confirms autocompleted form with Username/password.

IE: The approach mentioned for firefox didn't work for me. IE does offer to remember password, but even if you check this option, credentials don't get stored. (Maybe someone has solution for that).

The following is what does work: You add the site to Local Intranet Zone (Tools -> Internet options -> Security -> Local Intranet -> Sites -> Advanced). By default Security level is set up in the way that IE should attempt to authenticate you automatically using current user credentials. You can check that by clicking Custom level, then search for user authentication section. If either Automatic logon only in intranet zone or Automatic logon with current user name and password is selected, this shoud work.

Of course instead using Intranet zone you can add site in Trusted zone or somewhere else. Just make sure that Automatic logon with current user name and password options is selected.