The HTTP request is unauthorized with client authentication scheme Ntlm

Question

While calling a web service I get the following error      The HTTP request is unauthorized with client authentication scheme  NTLM   The authentication header received from the server was  NTLM   The HTTP request is unauthorized with client authentication scheme  NTLM   The authentication header received from the server was  NTLM     I have a Silverlight 4 application that calls a WCF web service  both on my IIS  7   my WCF web service calls another ASMX web service  installed on a different web server  using NTLM  Windows Authentication   Both servers  mine and the one hosting the ASMX web service are in the same domain   When the Silverlight client opens the application from the server using http   localhost MySiteName everything works fine  But when the Silverlight client opens the application from a different client  which is not the server but still in the same domain  using http   MyServerName MySiteName then I get the error   Windows Authentication is enabled in my IIS  Anonymous Authentication is disabled in my IIS   Binding configuration for calling my WCF web service is        lt binding name  winAuthBasicHttpBinding  gt         lt security mode  TransportCredentialOnly  gt           lt transport clientCredentialType  Windows    gt         lt  security gt       lt  binding gt    Binding configuration for calling the ASMX web service is        lt binding name  ClNtlmBinding  gt         lt security mode  TransportCredentialOnly  gt           lt transport clientCredentialType  Ntlm    gt         lt  security gt       lt  binding gt

User · Answer

1  I had to do the following with my configuration   Add BackConnectionHostNames or Disable Loopback Check  http   support microsoft com kb 896861  2  I was working off a dev system on an isolated dev network   I had gotten it working using the dev system s computer name in the URL to the web service  but when I modified the URL to the URL that would be used in production  rather than the computer name   I started getting the NTLM error   3  I noticed the security log showed that the service account failing to login with an error similar to the one in the MSDN article   4  Adding the BackConnectionHostNames made it so I could log into the server via a browser running on the server  but the service account still had NTLM errors when trying to authenticate for the web services   I wound up disabling the loop back check and that fixed it for me

User · Answer

It s a long time since the question was posted  but I experienced the same issue in a similar scenario  I have a console application and I was consuming a web service and our IIS server where the webservice was placed has windows authentication  NTLM  enabled   I followed this link and that fixed my problem  Here s the sample code for App config    lt system serviceModel gt       lt bindings gt           lt basicHttpBinding gt               lt binding name  Service1Soap  gt                   lt security mode  TransportCredentialOnly  gt                       lt transport clientCredentialType  Ntlm  proxyCredentialType  None                          realm     gt                       lt message clientCredentialType  UserName  algorithmSuite  Default   gt                   lt  security gt               lt  binding gt           lt  basicHttpBinding gt       lt  bindings gt       lt client gt           lt endpoint address  http   localhost servicename service1 asmx               binding  basicHttpBinding  bindingConfiguration  ListsSoap   gt       lt  client gt   lt  system serviceModel gt

User · Answer

I had to move domain  username  password from     client ClientCredentials UserName UserName   domain          username       client ClientCredentials UserName Password   password   to     client ClientCredentials Windows ClientCredential UserName   username    client ClientCredentials Windows ClientCredential Password   password    client ClientCredentials Windows ClientCredential Domain   domain

User · Answer

OK  here are the things that come into mind    Your WCF service presumably running on IIS must be running under the security context that has the privilege that calls the Web Service  You need to make sure in the app pool with a user that is a domain user - ideally a dedicated user  You can not use impersonation to use user s security token to pass back to ASMX using impersonation since my WCF web service calls another ASMX web service  installed on a   different   web server Try changing Ntlm to Windows and test again      OK  a few words on impersonation  Basically it is a known issue that you cannot use the impersonation tokens that you got to one server  to pass to another server  The reason seems to be that the token is a kind of a hash using user s password and valid for the machine generated from so it cannot be used from the middle server     UPDATE  Delegation is possible under WCF  i e  forwarding impersonation from a server to another server   Look at this topic here

User · Answer

Maybe you can refer to   http   msdn microsoft com en-us library ms731364 aspx My solution is to change  2 properties authenticationScheme and proxyAuthenticationScheme to  Ntlm   and then it works   PS  My environment is as follow  - Server side   net 2 0 ASMX  - Client side   net 4

User · Answer

For me the solution was besides using  Ntlm  as credential type  similar as Jeroen K s solution  If I had the permission level I would plus on his post  but let me post my whole code here  which will support both Windows and other credential types like basic auth       XxxSoapClient xxxClient   new XxxSoapClient        ApplyCredentials userName  password  xxxClient ClientCredentials        private static void ApplyCredentials string userName  string password  ClientCredentials clientCredentials                clientCredentials UserName UserName   userName          clientCredentials UserName Password   password          clientCredentials Windows ClientCredential UserName   userName          clientCredentials Windows ClientCredential Password   password          clientCredentials Windows AllowNtlm   true          clientCredentials Windows AllowedImpersonationLevel   System Security Principal TokenImpersonationLevel Impersonation

User · Answer

My problem was   None admin users were getting  the http request is unauthorized with client authentication scheme  negotiate  asmx  on my asmx services   I gived read execute folder permissions for the none admin users and my problem was solved

[c#] The HTTP request is unauthorized with client authentication scheme 'Ntlm'

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