Represents the type of user authentication with this station.
portalAuth - The authentication lunched by portal pop-up program
which is need input username and passward,exclude MAC authentication.
authFree - There is no need others authentiaction,user will
surf internet after association.
associateAuth - Include WEP PSK 802.1X authentication.
macAuth - MAC Authentication apply with access device,
a Remote Authentication Dial-In User Service (RADIUS) server or
message netgate to realize fast authentication.