Packet Scheduling Against Stepping-Stone Attacks with Chaff

We consider scheduling packet transmissions in a network so that the efficiency of stepping-stone attacks can be severely restrained with the help of stepping-stone monitors. We allow the attacker to encrypt and pad the packets, perturb the timing of packets, and insert chaff packets, but the timing perturbation is subject to a maximum delay constraint. We show that if we randomize packet transmissions, then the attacker has to insert a large amount of chaff to evade detection completely. In particular, if all transmissions are scheduled as Poisson processes, then the fraction of attacking packets in the attacker´s traffic decreases exponentially with the length of the intrusion path