Showing papers by "Yan Chen published in 2008"

Botnet Research Survey

Abstract: Botnets are emerging threat with hundreds of millions of computers infected. A study shows that about 40% of all computers connected to the internet in the world are infected bots and controlled by attackers. This article is a survey of recent advances in botnet research. The survey classifies the botnet research into three areas: understanding botnets, detecting and tracking botnets, and defending against botnets. While botnets are widespread, the research and solutions for botnets are still in their infancy. The paper also summarizes the existing research and proposes future directions for botnet research.

Methods and apparatus for generating a data dictionary

Abstract: There is provided a method and system generate a data dictionary for searching data items stored in an information resource. In one embodiment, the system generates a list of synonyms for keywords entered in search queries to the system. A keyword and synonym form a token pair. Token pairs are evaluated according to a bidirectional divergence value calculated for distributions of search results, wherein the searches are based on the token pairs. Token pairs are then selected based on the divergence value. The selected token pairs are compiled into a data dictionary. In one embodiment, the data dictionary is a synonym dictionary used for user search query expansion to find matching items.

Accurate and Efficient Traffic Monitoring Using Adaptive Non-Linear Sampling Method

Abstract: Sampling technology has been widely deployed in measurement systems to control memory consumption and processing overhead. However, most of the existing sampling methods suffer from large estimation errors in analyzing small-size flows. To address the problem, we propose a novel adaptive non-linear sampling (ANLS) method for passive measurement. Instead of statically configuring the sampling rate, ANLS dynamically adjusts the sampling rate for a flow depending on the number of packets having been counted. We provide the generic principles guiding the selection of sampling function for sampling rate adjustment. Moreover, we derive the unbiased flow size estimation, the bound of the relative error, and the bound of required counter size for ANLS. The performance of ANLS is thoroughly studied through theoretic analysis and experiments under synthetic/real network data traces, with comparison to several related sampling methods. The results demonstrate that the proposed ANLS can significantly improve the estimation accuracy, particularly for small-size flows, while maintain a memory and processing overhead comparable to existing methods.

Honeynet-based Botnet Scan Traffic Analysis

Abstract: With the increasing importance of Internet in everyone’s daily life, Internet security poses a serious problem Now-a-days, botnets are the major tool to launch Internet-scale attacks A “botnet” is a network of compromised machines that is remotely controlled by an attacker In contrast of the earlier hacking activities (mainly used to show off the attackers’ technique skills), botnets are better organized and mainly used for the profit-centered endeavors For example, the attacker can make profit through Email spam [1], click fraud [2], game accounts and credit card numbers harvest, and extortion through DoS attacks Although thorough understanding and prevention of botnets are very important Currently, the research community gains only limited insight into botnets Several approaches can help to understand the botnet phenomena:

Load Balanced and Efficient Hierarchical Data-Centric Storage in Sensor Networks

Abstract: Several new sensor network applications build on scalable, energy-aware data-centric storage. Data-centric storage is typically achieved by hashing a high-level data name to a well-known routable node address. Despite significant work on any-to-any routing for sensor networks, most schemes do not provide a node address space that is amenable to the needs of data-centric storage. Our work focuses on the problem of designing a routing primitive suitable for data-centric storage that also meets typical sensor network goals of scalability, energy-efficiency and load-balance. In this paper, we present a new hierarchical Voronoi graph based routing algorithm (HVGR) that simultaneously achieves good scalability, efficiency in routing, and load balance in both routing and data storage. The region oriented routing scheme avoids overloading cluster headers by "short-cutting" routes before they actually hit cluster headers. The storage load balancing algorithm achieves uniform distribution of storage load.

Cognitive spectrum access with joint opportunistic power and rate control in fading channels

Abstract: In cognitive networks, power control is commonly applied to limit the interference caused by the cognitive radio to the primary userpsilas communication, while rate control seeks the way of rate adaptation that achieves the highest spectrum efficiency. In this paper, we combine these two techniques and jointly consider power and rate control in fading channels. In particular, we propose our joint opportunistic power and rate control (JOPRC) strategy for both single-channel and multi-channel scenarios. Our strategy applies opportunistic interference cancellation in rate adaptation and protects the outage probability on the primary link not to be degraded via opportunistic power adjustment. In multi-channel case, due to both total transmit power constraint and per-channel maximum power constraint, our JOPRC equals finding the solution of an intercepted water-filling problem with floating rocks, and the floating-rock water-filling (FRWF) algorithm is proposed to obtain that solution. Analysis of the ergodic rate of the cognitive user is given by numerical simulations.

Addendum to “Late Cenozoic magnetochronology and paleoenvironmental changes in the northern foreland basin of the Tian Shan Mountains” by Jimin Sun, Qinghai Xu, and Baochun Huang

Abstract: [1] Sun et al. (2007) constructed a magnetostratigraphic record of the Kuitun River section (Xinjiang Province, China) and reinterpreted a magnetostratigraphic record from the same section previously published by Charreau et al. (2005). In this paper, we show that Sun et al. miscorrelated their column with respect to that of Charreau et al. A compatible correlation, recognized by both sides, is presented.

The emplacement of the Montagne Noire axial zone (French Massif Central): New insights from petro-textural, geochronological and AMS studies

Abstract: In the southern French Massif Central, the Montagne Noire axial zone is a NE-SW elongated granitic-migmatitic dome surrounded by recumbently folded Palaeozoic sedimentary series with a southern vergence. From rim to core, the axial zone consists of micaschist, gneiss, augen orthogneiss, cordierite migmatite, and anatectic granites (Laouzas, Montalet). Syn- to late kinematic granitoids intrude the dome. The relative succession of events in Montagne Noire: 1-recumbent folding, 2-doming and 3-post-migmatitic granitoids intrusion is widely acknowledged. Conversely, the tectonic setting of the doming is disputed. The proposed models do not take into account the granitic and migmatitic structures, geochronology and dome core structure. Therefore, petro-textural and Magnetic Susceptibility Anisotropy studies and new monazite U-Th/Pb datings have been carried out in the Montagne Noire axial zone. The Montalet granite (333±4 Ma) is coeval with migmatization, and the Soulie granite (318±4 Ma) marks dome intrusion. In the dome axial zone rocks, magmatic, late-magmatic, tectonic and metamorphic textures have been recognized. Magnetic mineralogical study indicates that biotite is the main carrier of the magnetic susceptibility in granitic and migmatitic rocks, and that cordierite does not influence vectors directions. The attitude of the magnetic foliation complies with the preferred orientation of biotite, schlierens, enclaves and with migmatitic foliation observed in the field. The AMS fabric confirms the elliptical shape of the axial zone inferred from the migmatitic and gneissic envelope. The southward dipping foliation identified in both flanks is in agreement with an asymmetric dome. Moreover, the magnetic lineations exhibit a contrasting pattern with a dominant NE-SW trend, and a N-S one as well. The AMS features are in agreement with a diapiric component for the migmatite ascent. A model involving diapirism coeval with anticlinal stacking followed by extension discussed.