Is the work of real estate brokerage, in which a commission is received from both parties, Islamically permissible?

Real estate brokerage (mediation) is permissible under its conditions. If the intention is that clients offer you a commission to secure their properties with insurance companies, then this requires the permission of your employing company if the work is during official working hours, and that the insurance company be a cooperative-takaful one. As for commercial insurance companies, it is not permissible to insure with them due to the elements of gharar (excessive uncertainty) and maysir (gambling) present therein.