Packet traceback in mobile ad hoc networks (MANETs) is a technique for identifying the source and intermediaries of a packet forwarding path. While many IP traceback techniques have been introduced for packet attribution in the Internet, they are not directly applicable in MANETs due to unique challenges of MANET environments. In this work, we make the first effort to quantitatively analyze the impacts of node mobility, attack packet rate, and path length on the traceability of two types of well-known IP traceback schemes: probabilistic packet marking (PPM) and hash-based logging. We then present the design of an authenticated K-sized Probabilistic Packet Marking (AK-PPM) scheme, which not only improves the effectiveness of source traceback in the MANET environment, but also provides authentication for forwarding paths. We prove that AK-PPM can achieve asymptotically one-hop precise, and present the performance measurement of AK-PPM in MANETs with both analytical models and simulations.