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ABSTRACT: Intrusion prevention mechanisms and technologies cannot always prevent a well-funded and persistent adversary from penetrating information systems. Middleware is one area where a system can provide intrusion tolerance. Distributed object middleware is considered the most general kind of middleware, and the Common Object Request Broker Architecture (CORBA) is a widely adopted standard for distributed object middleware. The goal of our Intrusion Tolerant Distributed Object Systems (ITDOS) framework is to create an architecture for distributed object systems that can provide high reliability for mission-critical information systems by tolerating Byzantine (arbitrary) faults in object servers. CORBA systems are one of the potential middleware architectures that can be supported by the architecture. From a system-level point of view, this architecture provides additional security in the form of a firewall proxy that can monitor Byzantine fault-tolerant multicast (BFTM) messages at the enclave boundary and minimize the impact of certain denial of service (DoS) attacks.
DARPA Information Survivability Conference and Exposition, 2003. Proceedings; 05/2003
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Foundations of Intrusion Tolerant Systems, 2003 [Organically Assured and Survivable Information Systems]; 02/2003
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ABSTRACT: Distributed applications that share a dynamically changing state are increasingly being deployed in wide-area environments. Such applications must access the state in a consistent manner, but the consistency requirements vary significantly from other systems. For example, shared memory models, such as sequential consistency, focus on the ordering of operations, and the same level of consistency is provided to each process. In interactive distributed applications, the timeliness of updates becoming effective could be an extremely important consistency requirement, and it could be different across different users. We propose a system that provides both non-timed and time-sensitive read and write operations for dynamic shared state. For example, a timed read can be used by a process to read a recently written value, whereas a timed write can make a new value available to all readers within a certain amount of time. We develop a consistency model that precisely defines the semantics of timed and non-tinted read and write operations. A protocol that implements this model is also presented. We also describe an implementation and some performance measurements
Distributed Computing Systems, 2001. 21st International Conference on.; 05/2001
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ABSTRACT: A common class of wide-area distributed applications remotely collect time-varying data and send it to consumers around the network. Some examples of these include network management, stock ticker data and event logs. The environment in which these applications must operate often dictates the schemes for disseminating the data between the writers and the readers. If the transport channel can be optimized to match the application's behavior patterns and the network resource constraints, sufficient improvements in application-level quality of service (QoS) can be achieved. The PASS (Piecewise Asynchronous Sample Service) system addresses this problem by using a flexible system of interconnected servers. PASS servers are distributed geographically around the network and are connected to readers and writers using the CORBA protocol. The forwarding policies used by the servers and the server interconnections can be customized for each application. Thus, PASS acts like an application-level multicast service with variable forwarding policies. PASS has been used to disseminate the up/down status of a large number of devices to a network management system. The PASS forwarding policy used very little network bandwidth while responding to failures in half a network round-trip time
Distributed Computing Systems, 1999. Proceedings. 19th IEEE International Conference on; 02/1999
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ABSTRACT: As networks and the use of communications within applications continue to grow and find more uses, so too does the demand for more control and manageability of various “system properties” through middleware. An important component supporting an integrated property architecture is the concept of an object gateway, which is a quality-of-service (QoS)-aware element transparently inserted at the transport layer between clients and objects to provide managed communication behavior for the particular property being supported. In this paper, we introduce the concept of a QoS-oriented gateway to integrate a variety of QoS enforcement and implementation mechanisms controlling the underlying distributed interactions. We discuss the functions performed by such a component in achieving the desired overall end-to-end QoS, and the design considerations underlying our current implementation. We conclude with experiences to date with two variations of the gateway: one controlling managed latency and throughput using bandwidth allocation, and one controlling dependability through the coordination of object replicas
Object-Oriented Real-Time Distributed Computing, 1999. (ISORC '99) Proceedings. 2nd IEEE International Symposium on; 02/1999
