Due to constrained resources, DDoS attack is one of the biggest threats to MANET. IP traceback technique is useful to defend against such type of attacks, since it can identify the attack sources. Several types of traceback schemes have been proposed for wired networks. Among all the existing schemes, probabilistic packet marking (PPM) scheme might be the most promising scheme for MANET. However its performance in MANET is not as good as that in Internet. In this paper, a new scheme based on the codingtechnique (CT) is proposed for traceback in MANET. Furthermore, a new idea of Incremental traceback is raised to cope with the situation of incremental attack (ICT). We present the protocol design and conduct theoretical analysis of this scheme. Additionally, we conduct experiments to compare it with the traditional PPM scheme. The experimental results show that the new coding-based traceback scheme outperforms the PPM scheme in MANET.