Packet Marking Scheme have been proposed for achieving traceback of DoS attacks
which has several advantages such as short responding time and small resource consuming.Since the randomicity of the packet marking procedure
the number of the packets needed by the victim in reconstructing is much more than the minimum number of packets required
therefore resulting in the increase of the rate of false positives and the responding time.In this paper
a marking-in-order scheme is proposed
which need less packets in reconstructing procedure because of marking the packets in order by storing every target IP's marking state in a hash table.The scheme is more practical for its high efficiency.