Denial of service attack is among the hardest network problems.Several countermeasures are proposed for it in the literature

among which

Probabilistic Packet Marking(PPM) first developed by Savage et al is promising and has many variants.In these marking schemes

router marks packets with a probability which is fixed and uniform.Using fixed probability causes that many packets are needed for a victim to reconstruct the attack path(s).In this paper

an adaptive marking scheme is given

which reduces the number of packets needed for attack path reconstruction

thus also saves time for the victim and reduces the ability for attackers to spoof.