IIS 7.5 Fails When Accessing DB

I'm facing a weird problem : I have a simple WCF service that retrieves some data from the DB. When I host the service on local serviceHost everything works fine, but when I host the same service on local IIS (7.5 - windows 7) I get this exception: The Undelying provider failed on open.

I have some logging services inside the service and I found out that this exception occures only when the service calls some DB service (not one particular, any DB service). The strange thing is that when the service is not hosted on IIS this same DB call works fine.

开发者_开发技巧Things I've done: enabled ASP.NET impersonation on the IIS server -> didn't help.

Another thing : I'm using sql server 2008 express.

Other ideas ???

What security mechanism are you using? It's likely that you are using some sort of Kerberos/Windows Authentication and IIS is unable to pass those credentials to SQL server. This issue is sometimes referred to as the double hop issue and is typically solved by delegation (not ASP.NET delegation).

Link: Delegation and Impersonation

Assuming you are running the service in .NET 4.0 have a look in IIS and the Application Pool serving the application in question.

If the account running the application pool is ApplicationPoolIdentity look in your database that login "IIS AppPool\DefaultAppPool" has rights to access ayour database.

One of the simplest things to get pointed in the right direction is to check your windows event logs, particularly the security log. It may be telling you what's going on.

Check these on both the IIS machine and the DB machine.

Sounds to me like the most likely cause would be security.

In IIS 7.5 you have various security layers. Each AppPool has it's own security credentials which you might want to check.

Also the IIS Windows Service it self has security credentials. You might want to try setting this to Network Account if it's set to local account.

But the error message you posted is the generic WCF error. I would agree with Jim about looking in the event log for more detail. If you find it post it here.