16 resultados para isolado protéico (IP)

em Deakin Research Online - Australia


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Although TCP has emerged as the standard in data communication, the introduction of ATM technology has raised numerous problems regarding the effectiveness of using TCP over A TM networks, especially when video traffic performance is considered. This paper presents a simulation model for transmission performance of video traffic via ATM over TCP/IP. The interactivity between TCP/IP and ATM, generation of MPEG traffic and evaluation of traffic performance are implemented in the model. The design and implementation details of the model are carefully described. The experiments conducted using the model and experimental results are briefly introduced, revealing the capability of our model in simulating network events and in evaluating potential solutions to performance issues.

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IP spoofing is a technique used to gain unauthorized access to computers, whereby the intruder sends messages to a computer with an IP address indicating that the message is coming from a trusted host. It causes serious security problem in the cyber world, and is currently exploited widely in the information warfare. This paper at first introduces the IP spoofing attack through examples, technical issues and attacking types. Later its countermeasures are analysed in detail, which include authentication and encription, filtering and IP traceback. In particular, an IP traceback mechanism, Flexible Deterministic Packet Marking (FDPM) is presented. Since the IP spoofing problem can not be solved only by technology, but it also needs social regulation, the legal issues and economic impact are discussed in the later part.

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In this paper, we present a new approach, called Flexible Deterministic Packet Marking (FDPM), to perform a large-scale IP traceback to defend against Distributed Denial of Service (DDoS) attacks. In a DDoS attack the victim host or network is usually attacked by a large number of spoofed IP packets coming from multiple sources. IP traceback is the ability to trace the IP packets to their sources without relying on the source address field of the IP header. FDPM provides many flexible features to trace the IP packets and can obtain better tracing capability than current IP traceback mechanisms, such as Probabilistic Packet Marking (PPM), and Deterministic Packet Marking (DPM). The flexibilities of FDPM are in two ways, one is that it can adjust the length of marking field according to the network protocols deployed; the other is that it can adjust the marking rate according to the load of participating routers. The implementation and evaluation demonstrates that the FDPM needs moderately only a small number of packets to complete the traceback process; and can successfully perform a large-scale IP traceback, for example, trace up to 110,000 sources in a single incident response. It has a built-in overload prevention mechanism, therefore this scheme can perform a good traceback process even it is heavily loaded.

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IP source address spoofing exploits a fundamental weakness in the Internet Protocol. It is exploited in many types of network-based attacks such as session hijacking and Denial of Service (DoS). Ingress and egress filtering is aimed at preventing IP spoofing. Techniques such as History based filtering are being used during DoS attacks to filter out attack packets. Packet marking techniques are being used to trace IP packets to a point that is close as possible to their actual source. Present IP spoofing  countermeasures are hindered by compatibility issues between IPv4 and IPv6, implementation issues and their effectiveness under different types of attacks. We propose a topology based packet marking method that builds on the flexibility of packet marking as an IP trace back method while overcoming most of the shortcomings of present packet marking techniques.

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This paper, using the Unconstrained Shape Matrix Optimization Problem as a test bed, we investigate various aspects of variable aggregation and disaggregation for a class of integer programs that contains binary expansion. We present theoretical and numerical results, and propose an iterative algorithm for exact solutions.

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Internet Protocol (IP) traceback is the enabling technology to control Internet crime. In this paper, we present a novel and practical IP traceback system called Flexible Deterministic Packet Marking (FDPM) which provides a defense system with the ability to find out the real sources of attacking packets that traverse through the network. While a number of other traceback schemes exist, FDPM provides innovative features to trace the source of IP packets and can obtain better tracing capability than others. In particular, FDPM adopts a flexible mark length strategy to make it compatible to different network environments; it also adaptively changes its marking rate according to the load of the participating router by a flexible flow-based marking scheme. Evaluations on both simulation and real system implementation demonstrate that FDPM requires a moderately small number of packets to complete the traceback process; add little additional load to routers and can trace a large number of sources in one traceback process with low false positive rates. The built-in overload prevention mechanism makes this system capable of achieving a satisfactory traceback result even when the router is heavily loaded. The motivation of this traceback system is from DDoS defense. It has been used to not only trace DDoS attacking packets but also enhance filtering attacking traffic. It has a wide array of applications for other security systems.

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This presentation will start with a brief review of the first phase of this project, which focused largely on the impact on innovation of legal and institutional IP reforms in Asia triggered by the WTO Agreement on Trade Related Intellectual Property Rights (TRIPS) and by subsequent bilateral or multilateral Free Trade Agreements (FTAs). The presentation will then show the emerging issues relevant for the second phase of the project, which in an increasingly diversified IP landscape will lie at the intersection of IP with other disciplines and other areas of law, such as competition law, media law, criminal law, human rights, environmental law and constitutional law.

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In advanced capitalist societies, intellectual property laws protecting such subject matter as copyright and patents are justified by a combination of theories, which include the provision of economic incentives to foster creativity and innovation and the prevention of unfair competition. IP academics and policy makers have differing views about the appropriate balance between these objectives and public interest considerations such as health, education and the protection of the environment. These different views entered the policy debate in Asian developing countries in connection with an unprecedented introduction and expansion of IP laws over the last 25 years. This paper will use case studies of law reform from Asia, in particular Southeast Asia, to show that the policy considerations of governments in reforming their laws were often quite different from the standard rationale mentioned above. As much of the IP was, at least initially, held by foreigners and introduced to attract foreign investment, national development considerations were joined with the more commonly quoted objectives to promote the rights, creativity and innovation of individuals. Such national development objectives at times coincided and at other times collided with official explanations and received wisdom about the effects of stronger IP rights.

Especially in the early postcolonial period, copyright laws and other IP laws were frequently restricted or simply not implemented, if they conflicted with development policies in areas such as education or public health. Such policies were slowly changing in the wake of WTO-TRIPS and other international agreements. Nevertheless, the implementation and enforcement of the IP laws has been uneven. Specialised institutions such as courts and IP administering agencies compete with other branches of government and administration for limited funding and a rich repertoire of informal dispute settlement procedures has kept the number of court cases relatively low. In some countries, censorship laws have influenced freedom of expression and led to quite idiosyncratic interpretations of intellectual property laws. Governments often also retain a role in the assessment of licensing and technology transfer contracts. And while there are many programs to foster individual creativity, in most cases R & D activities are still largely taking place in government institutions and this has influenced the thinking about intellectual property rights and creativity in the context of employment.

The paper uses a few case studies to examine the implementation of IP laws in selected Asian developing countries to point to the quite different institutional setting for IP law reform in comparison to European or American models. It reaches some tentative conclusions as to the likely effects on creativity and innovation under these different circumstances.

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The contributions to this book show the strategies and policies of countries in the Asia-Pacific region that have to grapple with international standard setting in what has been called the ‘spaghetti bowl’ of criss-crossing free trade agreements. The chapters show how intellectual property is just one among many political and economic factors that are used in trade off discussions. It leads to an often considerable further raising of IP standards in those countries that agree to higher protection levels, often for reasons that have little to do with the provision of incentives for technological progress. A more nuanced picture of IP protection in Asia shows the different interests of high protection countries, ‘first’ and ‘second tier’ newly industrialized and industrializing countries and the rather peculiar position of Australia and New Zealand. The chapter introduces the contributions to this volume according to these various groups of countries and of international law and the political economy of the region.

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DDoS attack source traceback is an open and challenging problem. Deterministic packet marking (DPM) is a simple and effective traceback mechanism, but the current DPM based traceback schemes are not practical due to their scalability constraint. We noticed a factor that only a limited number of computers and routers are involved in an attack session. Therefore, we only need to mark these involved nodes for traceback purpose, rather than marking every node of the Internet as the existing schemes doing. Based on this finding, we propose a novel marking on demand (MOD) traceback scheme based on the DPM mechanism. In order to traceback to involved attack source, what we need to do is to mark these involved ingress routers using the traditional DPM strategy. Similar to existing schemes, we require participated routers to install a traffic monitor. When a monitor notices a surge of suspicious network flows, it will request a unique mark from a globally shared MOD server, and mark the suspicious flows with the unique marks. At the same time, the MOD server records the information of the marks and their related requesting IP addresses. Once a DDoS attack is confirmed, the victim can obtain the attack sources by requesting the MOD server with the marks extracted from attack packets. Moreover, we use the marking space in a round-robin style, which essentially addresses the scalability problem of the existing DPM based traceback schemes. We establish a mathematical model for the proposed traceback scheme, and thoroughly analyze the system. Theoretical analysis and extensive real-world data experiments demonstrate that the proposed traceback method is feasible and effective.

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The expected pervasive use of mobile cloud computing and the growing number of Internet data centers have brought forth many concerns, such as, energy costs and energy saving management of both data centers and mobile connections. Therefore, the need for adaptive and distributed resource allocation schedulers for minimizing the communication-plus-computing energy consumption has become increasingly important. In this paper, we propose and test an efficient dynamic resource provisioning scheduler that jointly minimizes computation and communication energy consumption, while guaranteeing user Quality of Service (QoS) constraints. We evaluate the performance of the proposed dynamic resource provisioning algorithm with respect to the execution time, goodput and bandwidth usage and compare the performance of the proposed scheduler against the exiting approaches. The attained experimental results show that the proposed dynamic resource provisioning algorithm achieves much higher energy-saving than the traditional schemes.