The Natorm Group Communication Mechanism For Intrusion Tolerant System

The ITS (Intrusion Tolerant System) aims at guaranteeing the continuity of essential services despite errors brought about by attackers or arbitrary faults. In this work, the ITS has replicated group members communicating with each other by messages. In this situation, group communication should satisfy the reliability and total-ordered properties to maintain consistency among the replicated members. However, it requires additional communication overheads. To apply ITS in the real world, such an overhead should be minimized so as not to greatly affect the target service. As a solution to the problem, we propose a newly defined ITS group communication scheme, called the NATORM (NACK-based Total-ordered Reliable Multicast scheme), which requires little communication overhead and satisfies the properties for ITS. The NATORM is a cost-effective group communication mechanism, based on NACK messaging to notice which message is not received. The NATORM showed that it requires little communication overheads when the system environment is stable. To evaluate the suggested mechanisms, modeling and simulation have been performed and developments achieved.