So far, the problem of positioning and distance measurements in wireless networks has been studied in a non-adversarial setting. In this work, we analyze the resistance of positioning techniques to position and distance modification attacks; we propose two mechanisms for the position verification, based on multilateration and Time Difference Of Arrival (TDOA) techniques. We further propose two mechanisms for verification of nodes' mutual distances; we base these mechanisms on GPS and radar technologies. In our mechanisms, we make use of conventional distance estimation and cryptographic techniques.