Speaker: Sencun Zhu Title: Online Traceback in Mobile Ad Hoc Networks: Traceability Analysis and An Efficient Construction Abstract: While IP traceback techniques are powerful to identify the sources of Distributed Denial-of-Service (DDoS) attacks in the Internet and have been extensively studied in the past years, they are not directly applicable to tracing the attack sources in mobile ad hoc networks (MANETs). Two unique challenges exist. First, packet forwarding paths are easy to change due to node mobility, which causes the difficulty to reconstruct the attack paths. Second, forwarding nodes cannot be as much trusted as fixed routers in the Internet environment, and compromised nodes may collude in DoS attacks. In this work, we make the first effort to quantitatively analyze the impacts of node mobility, attack packet rate, and intrusion response time on the traceability of two types of well-known IP traceback schemes: probabilistic packet marking (PPM) and hash-based logging. Then, based on the principle of divide and conquer, we propose an efficient online traceback scheme. Through simulation we show that each traceback of our scheme can attribute to a small hotspot where the attack source resides and the attack source will receive the lowest reputation after multiple-round tracebacks.