title: MongoDB Error: "not authorized for query on admin.system.users"
body: <p>How to setup authentication on MongoDB using the following configuration ? </p>
  
  <p>2 mongoD instances, sharded collections.<br>
  1 mongoS instance on another server. <br>
  1 mongoD as a config server.</p>
  
  <p>Whenever a turn on auth on mongod, i'm not enabled to logon on any servers, the users are created but i still can't login. The following error appear when trying to logon on mongoS instance:</p>
  
  <p><b> $err: "not authorized for query on admin.system.users" </b></p>