Unable to access AuthenticationAdmin service of WSO2 Identity server

Question

I have a new WSO2 Identity server. I need to access an axis web service AuthenticationAdmin of WSO2 3.2.3 to authenticate a user. I tried to follow several tutorials but none helped.

Issuing https://localhost:9443/services/AuthenticationAdmin gives following error on browser:

message: Access to service metadata for service: AuthenticationAdmin has been forbidden

description: Access to the specified resource (Access to service metadata for service: AuthenticationAdmin has been forbidden) has been forbidden.

And on console I get the error for the service not being found, as:

ERROR {org.apache.axis2.engine.AxisEngine} - The endpoint reference (EPR) for the Operation not found is /services/AuthenticationAdmin and the WSA Action = null. If this EPR was previously reachable, please contact the server administrator..

Please guide me..