Secure RabbitMQ with MQTT plugin on Docker

I am running RabbitMQ on Docker with the MQTT plugin. My Docker file is:

FROM rabbitmq

RUN rabbitmq-plugins enable --offline rabbitmq_management
RUN rabbitmq-plugins enable --offline rabbitmq_mqtt

EXPOSE 15671 15672
EXPOSE 1883

How can I secure the connection to the MQTT plugin? For example for authentication, the MQTT adapter can be configured to use user name/pass using allow_anonymous

How to change the RabbitMQ docker image configuration?

Thanks!