The use of simulations have become increasingly frequent in the study and the performance evaluation of network systems. The simulation environment deeply influences the behavior of results, so a model that simulates a realistic movement of the nodes is necessary for the study of wireless networks. Simple mobility models do not provide realistic scenarios. Often movements are completely random, uncorrelated and in open space, without the chance of considering the effects of obstacles or rules that limit and guide the movement. In this paper, we propose a more realistic model, studied for indoor environments (but applicable to outdoor models as well). Given the map of the obstacles in the simulation area (e.g., a floor plan), the nodes have the possibility to move in random walk just avoiding to cross the obstacles (e.g., walls), or following a specified virtual path that connects all the simulation area, or a hybrid of the two. Our tool creates a file containing the movement of the nodes during the whole simulation time. Simulation results show that nodes are highly dependent on the different obstacles maps and pathways. Furthermore, a mathematical demonstration is given to validate the results obtained by simulation in a simple case.