The HTTP request is unauthorized with client authentication scheme 'Ntlm'. The authentication header received from the server was 'Negotiate,NTLM'

Question

I've looked through a ton of SO articles, and even other sites, but can't seem to get this service working. I have a SOAP service I'm trying to hit and it's configured like this:

<system.serviceModel>
    <bindings>
        <basicHttpBinding>
        <binding name="PROVIDERSSoapBinding">
            <security mode="TransportCredentialOnly">
            <transport clientCredentialType="Ntlm" proxyCredentialType="None" realm="" />
            </security>
        </binding>
        </basicHttpBinding>
    </bindings>
    <client>
        <endpoint address="http://xxx.xx.xx.xxx:9011/provider/services/PROVIDERS"
            binding="basicHttpBinding" bindingConfiguration="PROVIDERSSoapBinding"
            contract="ServiceReference1.ProviderRemote" name="PROVIDERS" />
    </client>
</system.serviceModel>

However, I'm getting the following error when hitting it from my console application:

The HTTP request is unauthorized with client authentication scheme 'Ntlm'. The authentication header received from the server was 'Negotiate,NTLM'.

Can somebody help me out?

Answer 1

You can eliminate the client from the problem by using wftech, this is an old tool but I have found it useful in diagnosing authentication issues. wfetch allows you to specify NTLM, Negotiate and kerberos, this may well help you better understand your problem. As you are trying to call a service and wfetch knows nothing about WCF, I would suggest applying your endpoint binding (PROVIDERSSoapBinding) to the serviceMetadata then you can do an HTTP GET of the WSDL for the service with the same security settings.

Another option, which may be available to you is to force the server to use NTLM, you can do this by either editing the metabase (IIS 6) and removing the Negotiate setting, more details at http://support.microsoft.com/kb/215383.

If you are using IIS 7.x then the approach is slightly different, details of how to configure the authentication providers are here http://www.iis.net/configreference/system.webserver/security/authentication/windowsauthentication.

I notice that you have blocked out the server address with xxx.xx.xx.xxx, so I'm guessing that this is an IP address rather than a server name, this may cause issues with authentication, so if possible try targeting the machine name.

Sorry that I haven't given you the answer but rather pointers for getting closer to the issue, but I hope it helps.

I'll finish by saying that I have experienced this same issue and my only recourse was to use Kerberos rather than NTLM, don't forget you'll need to register an SPN for the service if you do go down this route.