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c#asp.net-web-api2owinrestsharpntlm

RestSharp and NTLM authentication does not work if accessing API via hostname

I am having a problem with NTLM authentication on Owin selfhosted Web Api. NTLM is enabled on both server and client side. In client I am using RestSharp.

Client

 _client = new RestClient(ConfigurationManager.AppSettings["UserAccessApi"]);
 _client.Timeout = 5000;
 _client.Authenticator = new NtlmAuthenticator();

Service

var listener =
 (System.Net.HttpListener)app.Properties["System.Net.HttpListener"];
listener.AuthenticationSchemes = System.Net.AuthenticationSchemes.IntegratedWindowsAuthentication;

app.UseWebApi(config);

If I access this API via IP or Chrome browser it just works, while if access it through hostname or internet explorer, it does not. I assume this is related to restsharp using httpclient which uses IE engine, which in our company has some local/public networks security settings which are getting in a way for IE. Anybody had similar issue and have any idea how to overcome it without going the "Change IE settings" way?

HostName based call header

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IP Based call header

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Fiddler log, 1st batch - hostname call, 2nd batch - ip

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Solution

  • Using AuthenticationSchemes.Ntlm should help. But it's more like a workaround, as it'll be forcing Ntlm.