How to fix "The HTTP request was forbidden with client authentication scheme 'Anonymous'"

Question

I'm having some issues implementing a client that talks to a WCF service. It's a WCF hosted by another company so I don't have access to its code. I used the Connected Service provider tool in Visual Studio to generate the client code so that I could make requests and everything works fine on my local machine. I am having an issue on our development environment where I receive the following error if I try to make a request with the client:

The HTTP request was forbidden with client authentication scheme 'Anonymous'

I've been looking at the client code (it's a lot of code) which is generated by the Provider tool and I think it may have something to do with the following block of code.

System.ServiceModel.BasicHttpBinding result = new System.ServiceModel.BasicHttpBinding();
result.MaxBufferSize = int.MaxValue;
result.ReaderQuotas = System.Xml.XmlDictionaryReaderQuotas.Max;
result.MaxReceivedMessageSize = int.MaxValue;
result.AllowCookies = true;
result.Security.Mode = System.ServiceModel.BasicHttpSecurityMode.Transport;
return result;

Answer 1

This more linked to firewall rules within corporate network.

I had same issue using non authorized proxy but got resolved secured proxy with ntlm ClientCredentialType

Answer 2

result.Security.Mode = System.ServiceModel.BasicHttpSecurityMode.Transport;

Security is provided using HTTPS. The service must be configured with SSL certificates. The SOAP message is protected as a whole using HTTPS. The service is authenticated by the client using the service's SSL certificate. The client authentication is controlled through the ClientCredentialType.

https://docs.microsoft.com/en-us/dotnet/api/system.servicemodel.basichttpsecuritymode?view=netframework-4.8

Answer 3

This error typically indicates that the WCF server authenticates the client-side with a certificate. The error will occur when the trust relationship between the server and the client have not been established yet.

In general, we need to provide client credential to be authenticated by the server so that be able to call the service. As for what kind of credentials need to be provided, it depends on the binding information on the server-side.

 BasicHttpBinding binding = new BasicHttpBinding();
            binding.Security.Mode = BasicHttpSecurityMode.Transport;
binding.Security.Transport.ClientCredentialType = HttpClientCredentialType.Windows;

Namely, the above errors have indicated that the server authenticates the client with a certificate.

binding.Security.Transport.ClientCredentialType = HttpClientCredentialType.Certificate;

About authenticating the client with a certificate, you could refer to the below link for details.
https://docs.microsoft.com/en-us/dotnet/framework/wcf/feature-details/transport-security-with-certificate-authentication
Feel free to let me know if there is anything I can help with.

Answer 4

Thanks for all the suggestions. This was actually just caused by a firewall rule that was setup within our organisation. Once that was removed the code worked as expected.