Legacy system authentication provides the ability to interoperate with older software that may not support authentication, by providing a mechanism.
When an incoming connection does not provide any authentication information, a server substitutes the standard username and password with
<DEFAULT>. After that substitution, the
<DEFAULT>/<DEFAULT> authentication information is validated in exactly the same way as any other username/password combination validation.
An incoming connection that explicitly specifies
<DEFAULT>/<DEFAULT> is permitted. It is treated in exactly the same way as a connection that provides no authentication information.