Study And Implement On Intrusion Tolerant Techniques Based On Process Migration

Modern society is growing increasingly dependent upon large-scale, unbounded network systems such as the Internet, whereas the occurrence of attacks or incidents is more and more frequent, which greatly threatens the security of network infrastructures. Therefore, due to need for protecting critical network infrastructures, the survivability of network infrastructures is studied. Intrusion tolerance is an approach to handling malicious attacks, and is also an important means for enhancing the survivability of network service. But current intrusion-tolerant server architectures are substantially an architecture based on a single node, and have not cooperation between network nodes, therefore, this thesis presents a distributed architecture based on process migration, and profoundly studies its key techniques. The primary contributions of this thesis include the following three parts.Firstly, a distributed architecture based on cooperation between network nodes is presented — a intrusion-tolerant server architecture based on process migration, and its core is the Network Server Process Dynamic Migration(NSPDM) technique. This architecture does not need a front end proxy to forward requests, thereby may avoid to cause a new security bottle-neck, and that uses process migration technique, thereby can provide continual services for users.Secondly, the key techniques of NSPDM are profoundly studied. The procedure in which process states are fetched and regenerated is simplified through the designed and implemented system calls: getprocinfo() and setprocinfo(); the process state informations are sent and received through the designed and implemented functions: sender() and receiver(); The location independence of migrated processes are implemented through the designed and implemented IP address rewriting function and IP packet forwarding function. The methods of solving migration scheduling questions are proposed: when numbers of migrated process are small, it is the simplest to migrate all processes to an available node in which load is the lightest; when numbers of migrated process are large, migrated processes may be more reasonably distributed through the efficient distributing algorithms.Finally, the external trigger and internal trigger are profoundly studied to solve the question of time when the processes are migrated. The research results show: they have their own advantages respectively, and adapt to different circumstances respectively. For the internal trigger, if the method of stochastic implementation is adopted, security can be insured.The exploration to the intrusion-tolerant techniques based on process migration has the significant practice meaning for improving the survivability of network service.