ITR: Collaborative Research: Resource Allocation and Denial of Service Prevention in Active Networks

Internet被一组快速扩展和变化的应用程序所使用。网络发展甚至提供特定于应用程序的处理的需求是非常重要的。然而，当前的网络基础设施很难发展，也不容易支持可定制性。主动网络[21,3,2]的目标是通过使网络基础设施可编程来促进这种演变和定制。增加可编程性的一种方法是允许将代码下载到路由器中，从而允许添加或修改服务。一种更激进的方法是允许数据包本身携带程序，在网络路由器上选择性地执行。在其他问题中，这两种方法增加了拒绝服务攻击的可能性，即用户为了拒绝另一个用户的访问而对网络资源提出过多的要求。然而，它们也提供了处理此类攻击的新方法，并解决了在网络中分配资源的一般问题。提出的研究重点是涉及可编程或活动数据包的问题。主动数据包在几个方面促进了拒绝服务攻击。首先，与传统的数据传输数据包不同，活动数据包可能需要处理器周期和路由器的内存，而不仅仅是简单地转发数据包。其次，一般来说，在路由器上执行一个活动包可能会导致从路由器传输多个活动包。这种行为是有用的，因为它允许数据包在网络上呈扇形散开，但它也有潜在的危险，因为它可能导致单个初始数据包所使用的资源呈指数级增长。基于主动数据包的系统的经验[9,8,23,22,24]表明，拒绝服务是在此类系统可行之前必须克服的最大障碍。拟议的研究从各个方面解决了这个问题。首先，研究人员建议设计数据包编程语言，使某些类型的行为本质上不可能。例如，在PLAN[9]中，包程序被保证终止，因此永远不会使用无限数量的路由器周期。研究人员将探索在资源需求方面限制行为和限制可表达性之间的权衡，从而限制活动数据包的灵活性。然而，并不是所有潜在的有害行为都可以通过这种方式消除。因此，在第二个方面，研究人员将考虑明确说明网络中数据包资源使用情况的机制。例如，每个数据包可能携带一个资源绑定，随着资源的使用而减少，当绑定耗尽时触发终止。提出的研究结合了控制资源使用的隐式和显式机制，以及控制网络流量的算法，以减少拒绝服务的可能性。更一般地说，可以设想评估在拥塞资源上执行的活动数据包的成本。因此，在第三个方面，研究人员建议研究基于拥塞成本的机制，以实现更有效的资源分配，以及如何通过活动数据包促进资源分配。将使用三种方法来验证提出的解决方案。首先，研究人员将利用数学模型来激励所提出的解决方案的好处和调查的特点。其次，研究人员将利用专业知识和过去在实现主动网络方面的工作来证明什么是可行的，并探索每种解决方案对最终应用的限制。最后，研究人员将使用网络模拟来研究在实验测试台上无法实现的规模系统。

The Internet is used by a rapidly expanding and changing set of applications. The need for the network to evolve and even to provide application specific processing is significant. However the current network infrastructure is hard to evolve and does not readily support customizability. The goal of Active Networking [21, 3, 2] is to facilitate this evolution and customization by making the network infrastructure programmable. One way of adding programability is to allow code to be down-loaded into the routers, thus enabling the addition or modification of services. A more radical approach is to allow the packets themselves to carry programs to be executed selectively on the network's routers. Among other issues, these two approaches increase the possibility of denial of service attacks whereby a user places excessive demands on network resources in order to deny access to another user. However, they also enable new approaches to handling such attacks and to addressing the general problem of allocating resources within the network.The proposed research focuses on issues involving programmable, or active, packets. Active packets facilitate denial of service attacks in several ways. First, unlike conventional data transport packets, an active packet may require processor cycles and memory at the routers beyond those needed to simply forward the packet. Second, in general, the execution of an active packet at a router may cause more than one active packet to be transmitted from the router. Such behavior is useful, since it allows a packet to fan out across the network, but it is potentially dangerous since it can lead to an exponential growth in the resources used by a single initial packet. Experience with active packet-based systems [9, 8, 23, 22, 24] suggests that denial of service is the single biggest obstacle which must be overcome before such systems are feasible.The proposed research tackles this problem along various fronts. First, the researchers propose to design packet programming languages that make some types of behavior intrinsically impossible. For example, in PLAN [9], packet programs are guaranteed to terminate and thus can never use an un-bounded number of router cycles. The researchers will explore tradeoffs between restricting behavior in terms of resource requirements and limiting the expressibility and thus the flexibility of active packets. However, not all potentially harmful behaviors can be eliminated in this manner. Thus, on a second front, the researchers will consider mechanisms that explicitly account for a packet's resource usage in the network. For example, each packet may carry a resource bound, which is decremented as resources are used, and which triggers termination when the bound is used up. The proposed research combines both implicit and explicit mechanisms for controlling resource usage, with algorithms to control the flow of traffic into the network to decrease the likelihood of denial of service. More generally, one can envisage assessing costs to active packets that execute on congested resources. Thus, on a third front, the researchers propose to investigate mechanisms based on congestion costs to achieve more efficient resource allocations and how they can be facilitated via active packets.Three methodologies will be used to validate proposed solutions. First, the researchers will draw on mathematical modeling to motivate the benefits and investigate the characteristics of the proposed solutions. Second, the researchers will leverage expertise and past work on implementing active networks to demonstrate what is feasible to build, and explore the constraints each solution will place on eventual applications. Finally, the researchers will use network simulation to investigate systems on a scale not achievable on the experimental testbeds.