Under the laws of all states in this country, a landlord is entitled to access of a rental by giving the tenant reasonable notice. Typically 24 hours is reasaonable notice for the landlord to show a unit for lease of sale.Custom and practice in the industry is for a real estate agent to place a lock box on the door for selling agents to get access. The lock box is allowable. However, you are entitled to reasonable notice (24 hours minimum) when some real estate agent wishes to view the rental.