A TCAM-based solution for integrated traffic anomaly detection and policy filtering

The survivability of the future Internet is largely dependent on whether it will be able to successfully address both security and performance issues facing the Internet. On one hand, the Internet becomes more and more vulnerable due to fast spreading malicious attacks. On the other hand, it is under great stress to meet ever growing/changing application demands while having to sustain multi-gigabit forwarding performance. In this paper, we propose a Ternary Content Addressable Memory (TCAM) coprocessor based solution for high speed, integrated TCP flow anomaly detection and policy filtering. The attacking packets with spoofed source IP addresses are detected through two-dimensional (2D) matching. The key features of the solution are: (1) setting flag bits in TCAM action code to support various packet treatments; (2) managing TCP flow state in pair to do 2D matching. We evaluate the solution’s ability to detect TCP-based flooding attacks based on real-world-trace simulations. The results show that the proposed solution can match up OC-192 line rate. The possible modifications of the solution for the detection of low rate TCP-targeted attacks are also discussed.     

Utility function of TCP

Understanding the TCP congestion control mechanism from a global optimization point of view is not only important in its own right, but also crucial to the design of other transport layer traffic control protocols with provable properties. In this paper, we derive a global utility function and the corresponding optimal control law, known as TCP control law, which maximizes the global utility. The TCP control law captures the essential behaviors of TCP, including slow start, congestion avoidance, and the binary nature of congestion feedback in TCP. We find that the utility function of TCP is linear in the slow start phase and is proportional to the additive increase rate and approaches the well-known logarithm function as the data rate becomes large in the congestion avoidance phase. We also find that understanding the slow start phase with a fixed threshold is critical to the design of new transport layer control protocols to enable quality of service features. Finally, as an application, we design a Minimum Rate Guaranteed (MRG) traffic control law that shares the same utility function as the TCP control law. Our simulation study of the MRG control law indicates that it is indeed TCP friendly and can provide minimum rate guarantee as long as the percentage of network resource consumed by the MRG flows is moderately small.     

Visual topic discovering,tracking and summarization from social media streams

Multimedia Tools and Applications - Nowadays, microblogging has become popular, with hundreds of millions of short messages being posted and shared every minute on a variety of topics in social...     

一个利用EMAIL实现分布数据共享的方法

文章介绍一种利用Email实现分布数据共享的方法。文中先对该方法的几个要点进行了描述,之后介绍了该方法的设计和实现过程,最后介绍了它在好来西CIMS系统中的应用。     

The locally definable property of the product control structure

In this paper, the control structures and control technologies in decentralized discrete event control system are investigated. It shows that if the control structures on two local systems are standard and locally definable, so is the product control structure. Furthermore, a control technology associated with the product control structure is also given     

实现多系统间的数据交换

为企业原有应用系统之间进行数据交换提供了一种较为通用的方法,既有效克服了系统间数据表结构不一致的问题,同时也不限制进行数据交换的数据表。     

Fine analysis on advanced detection of transient electromagnetic method

Fault fracture zones and water-bearing bodies in front of the driving head are the main disasters in mine laneways, thus it is important to perform their advanced detection and prediction in advance in order to provide reliable technical support for the excavation. Based on the electromagnetic induction theory, we analyzed the characteristics of primary and secondary fields with a positive and negative wave form of current, proposed the fine processing of the advanced detection with variation rate of apparent resistivity and introduced in detail the computational formulae and procedures. The result of physical simulation experiments illustrate that the tectonic interface of modules can be judged by first-order rate of apparent resistivity with a boundary error of 5%, and the position of water body determined by the fine analysis method agrees well with the result of borehole drilling. This shows that in terms of distinguishing structure and aqueous anomalies, the first-order rate of apparent resistivity is more sensitive than the second-order rate of apparent resistivity. However, some remaining problems are suggested for future solutions.     

一种与材料状态相关的砂土剪胀性理论模型

结合密砂和中密砂的相变点的概念,提出了以相变状态为参考状态的状态参量表达式,并将此状态参数引入剪胀比的计算公式.在修正剑桥模型的基础上,提出了新的塑性势函数和硬化参数表达式以消除应力路径的影响.在增量塑性理论的基础上,建立了一种适合于密砂和中密砂的与材料状态相关的剪胀性理论模型.     

地方高校体育场馆开放管理对策研究——以常州某高校为例

对某高校体育场馆开放管理情况进行了调查分析,并就存在的问题提出对策。通过调查发现,高校体育场馆开放管理存在的主要问题是缺乏专业管理、场馆供需矛盾、设施不完善、开放不完全、无形资产开发明显不足等,并对此提出以下策略:加强专业管理、改造完善体育馆设施、树立正确的开放意识和良好的服务意识、加大宣传、积极开展无形资产经营等。     

基于CATIA平台的水电工程料场开采三维设计

为了给水电工程施工总体布置提供直接有效的信息反馈,利用CATIA三维设计分析平台,结合某水电工程施工设计中料场区域的实际地质情况,建立了料场区域三维实体分析模型,实现了开采区域的三维化设计。模型运用表明,将CATIA三维设计技术应用于料场开采设计工程实际,不仅可以直观反映料场区域地形地貌特征,还可以快速地给出料场开采体工程量和支护面工程量,提高了工程用料开采计算精度和设计工作效率。