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An attractive target for a computer system attacker is the router. An attacker in control of a router can disrupt communication by dropping or misrout-ing packets passing through the router. We present a protocol called W ATCHERS that detects and reacts to routers that drop or misroute packets. WATCHERS is based on the principle of conservation of ow in a(More)
Several concurrent programming languages and systems — e.g., MPI, .NET, and SR — provide mechanisms to facilitate communication between one process and a group of others. One such mechanism is SR's concurrent invocation statement (co statement). It specifies a group of operation invocations and normally terminates when all of its invo-cations have(More)
The goal of this research is to develop a method to detect malicious code (e.g. computer viruses, worms, Trojan horses, and time/logic bombs) and security-related vulnerabilities in system programs. The Malicious Code Filter (MCF) is a pro-grammable static analysis tool developed for this purpose. It allows the examination of a program before installation,(More)
SR is a language for programming distributed systems ranging from operating systems to application programs. On the basis of our experience with the initial version, the language has evolved considerably. In this paper we describe the current version of SR and give an overview of its implementation. The main language constructs are still resources and(More)
SUMMARY This paper describes a novel approach to event-based debugging. The approach is based on a (coarse-grained) dataflow view of events: a high-level event is recognized when an appropriate combination of lower-level events on which it depends has occurred. Event recognition is controlled using familiar programming language constructs. This approach is(More)