How can I avoid unauthorized agents or middlemen?

Deal only within the licensed recruitment agency’s official address; in some countries, the law provides specific places or addresses where they can recruit, and this usually refers to their official address
Check the identity of the agent or middleman; in some countries where agents or middlemen are allowed, they usually have a special power, authority or license to recruit but in Bangladesh Middleman are not recognized.so avoid middleman.
Ask for official receipt or invoice for every fee paid