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Abstract. Current intrusion detection systems have a narrow scope. They target flow aggregates, reconstructed TCP streams, individual packets or application-level data fields, but no existing solution is capable of handling all of the above. Moreover, most systems that perform payload inspection on entire TCP streams are unable to handle gigabit link rates. We argue that network-based intrusion detection systems should consider all levels of abstraction in communication (packets, streams, layer-7 data units, and aggregates) if they are to handle gigabit link rates in the face of complex application-level attacks such as those that use evasion techniques or polymorphism. For this purpose, we developed a framework for network-based intrusion prevention at the network edge that is able to cope with all levels of abstraction and can be easily extended with new techniques. We validate our approach by making available a practical system, SafeCard , capable of reconstructing and scanning TCP streams at gigabit rates while preventing polymorphic buffer-overflow attacks, using (up to) layer-7 checks. Such performance makes it applicable in-line as an intrusion prevention system. SafeCard merges multiple solutions, some new and some known. We made specific contributions in the implementation of deep-packet inspection at high speeds and in detecting and filtering polymorphic buffer overflows.

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Data parallel languages, like High Performance Fortran (HPF), support the notion of distributed arrays. However, the implementation of such distributed array structures and their access on message passing computers is not straightforward. This holds especially for distributed arrays that are aligned to each other and given a block-cyclic distribution.In this paper, an implementation framework is presented for HPF distributed arrays on message passing computers. Methods are presented for efficient (in space and time) local index enumeration, local storage, and communication.Techniques for local set enumeration provide the basis for constructing local iteration sets and communication sets. It is shown that both local set enumeration and local storage schemes can be derived from the same equation. Local set enumeration and local storage schemes are shown to be orthogonal, i.e., they can be freely combined. Moreover, for linear access sequences generated by our enumeration methods, the local address calculations can be moved out of the enumeration loop, yielding efficient local memory address generation.The local set enumeration methods are implemented by using a relatively simple general transformation rule for absorbing ownership tests. This transformation rule can be repeatedly applied to absorb multiple ownership tests. Performance figures are presented for local iteration overhead, a simple communication pattern, and storage efficiency.

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In this paper we present a generalized forall statement for parallel languages. The forall statement occurs in many (data) parallel languages and specifies which computations can be performed independently. Many different definitions of such a construct can be found in literature, with different conditions and execution models. We will show how forall constructs of a wide class of parallel languages can be mapped to this generalized forall statement. In addition, the forall statement we propose has the ability to spawn more complex independent activities than can be found in these languages. Denotational semantics are used to define the meaning of the forall and define only one possible program state change. It is shown that it is easy to use and that it is feasible to implement this forall efficiently.

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