Can anyone give a clear explanation of the difference between using

  • clientCredentialType=Windows, and
  • clientCredentialType=Ntlm

in a server-side Web.config when hosting a WCF service?

I have a SOAP 1.1 (basicHttpBinding) service for interop with existing clients. It uses ASP.NET roles so needs clients to be authenticated.

When I am using the VS2005 (Cassini) server to host the service, I have to specify ClientCredentialType=Ntlm as above, and check the Ntlm authentication box in the project properties in VS2005. ClientCredentialType=Windows doesn't work - clients get a:

401 Unauthorized error

However when I'm running under IIS, it's the other way around: ClientCredentialType=Windows works, and ClientCredentialType=Ntlm fails.

Can anyone explain this, and preferably suggest a way I can have the same web.config file to run the service in Cassini and IIS?

Update

I have .NET 3.5 SP1 on my dev machine, which is XP SP2 running in a domain. Cassini therefore runs under a domain account, and IIS 5.1 under a local account.

I wonder if it could be related to the breaking change in .NET 3.5SP1 described in these articles.

http://www.aspnetpro.com/newsletterarticle/2008/12/asp200812ab_l/asp200812ab_l.asp http://msmvps.com/blogs/alvin/archive/2008/11/14/net-3-5-sp1-breaking-change-to-wcf.aspx http://connect.microsoft.co

wcf visual-studio-2005 cassini
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