title: Allow anonymous access to a single WCF service method
body: <p>I have a WCF service with message security and Username credentials. Most of my methods are starting with </p>
  
  <pre><code>[PrincipalPermission(SecurityAction.Demand, Role = ConstStrings.Roles.Admin)]
  </code></pre>
  
  <p>and these methods are supposed to be called only by authenticated users. </p>
  
  <p>I want to add a method which would be called by an anonymous, but I receive an error:</p>
  
  <blockquote>
    <p>The username is not provided. Specify username in ClientCredentials.</p>
  </blockquote>
  
  <p>I am loking for something similar to MVC's <code>[AllowAnonymous]</code> attribute</p>