mex endpoint 只能以匿名方式访问。如果需要更新Silverlight 服务引用，需要同时开启IIS的匿名访问方式

1. 在web.config中开启windows authentication

<authentication mode="Windows" />

2. 配置basicHttpBinding

<system.serviceModel>

<bindings>

<basicHttpBinding>

<binding name="BasicHttpEndpointBinding">

<security mode="TransportCredentialOnly">

<transport clientCredentialType="Windows" />

</security>

</binding>

</basicHttpBinding>

</bindings>

<services>

.........

.........

</system.serviceModel>