1,720,977 research outputs found
Lee, Gunhee
No full text학위논문(박사)--아주대학교 정보통신전문대학원 :정보통신공학과,2009. 2ACKNOWLEDGEMENT --------------------------------------------------------------- I
ABSTRACT ---------------------------------------------------------------------- III
TABLE OF CONTENTS ------------------------------------------------------------- V
LIST OF FIGURES --------------------------------------------------------------- X
LIST OF TABLES ---------------------------------------------------------------- XII
CHAPTER 1 INTRODUCTIONS ------------------------------------------------------- 1
1.1 ROUTING MISBEHAVIOR IN WIRELESS AD HOC NETWORKS -------------------------- 2
1.2 SCOPE AND GOAL OF THE DISSERTATION --------------------------------------- 9
1.3 STRUCTURE OF THE DISSERTATION -------------------------------------------- 9
CHAPTER 2 WIRELESS AD HOC NETWORKS AND SECURITY ------------------------------- 11
2.1 OVERVIEW OF ROUTING PROTOCOLS -------------------------------------------- 11
2.2 SECURITY SERVICES AND CHALLENGES ----------------------------------------- 17
2.3 SECURITY ATTACKS ON ROUTING PROTOCOL ------------------------------------- 19
2.3.1 Attacks using Impersonation ------------------------------------------- 20
2.3.2 Attacks using Modification -------------------------------------------- 22
2.3.3 Attacks using Fabrication --------------------------------------------- 23
2.3.4 Replay Attacks -------------------------------------------------------- 29
2.3.5 Denial of Service (DoS) Attacks --------------------------------------- 29
2.4 SECURE ROUTING PROTOCOLS ------------------------------------------------- 32
2.4.1 Secure Efficient Ad hoc Distance Vector (SEAD) ------------------------ 33
2.4.2 ARIADNE --------------------------------------------------------------- 34
2.4.3 Security Aware Routing (SAR) ------------------------------------------ 35
2.4.4 Secure Routing Protocol (SRP) ----------------------------------------- 36
2.4.5 Secure Routing Protocol for Ad Hoc Networks (ARAN) -------------------- 37
2.4.6 Security Protocols for Sensor Network (SPINS) ------------------------- 39
2.4.7 Cooperation of Nodes Fairness in Dynamic Ad hoc Networks (CONFIDANT) -- 40
2.4.8 Defense Mechanisms against Rushing Attacks ---------------------------- 41
2.4.9 Defense Mechanisms against Wormhole Attacks --------------------------- 42
2.4.10 Defense Mechanisms against Sybil Attacks ----------------------------- 43
2.4.11 Security Mechanisms for Broadcast Operation -------------------------- 45
2.4.12 Limitation of the Secure Routing Protocols --------------------------- 47
2.5 INTRUSION DETECTION SYSTEM FOR MANETS ------------------------------------ 47
2.5.1 Distributed IDS for Ad Hoc Networks ----------------------------------- 48
2.5.2 AODV Protocol-based IDS ----------------------------------------------- 49
2.5.3 Techniques for Intrusion-Resistant Ad Hoc Routing Algorithms ---------- 51
2.5.4 Distributed Intrusion Detection Using Mobile Agents ------------------- 52
2.5.5 Local Intrusion Detection System -------------------------------------- 54
2.5.6 Watch Dog and Pathrather ---------------------------------------------- 56
2.6 PREVENTING ROUTING MISBEHAVIOR ---------------------------------------- 56
2.6.1 Credit-Based Schemes -------------------------------------------------- 57
2.6.2 Reputation-Based Schemes ---------------------------------------------- 58
2.6.3 End-to-end Acknowledgment Schemes ------------------------------------- 59
2.6.4 Other Prior State-of-the-art Schemes ---------------------------------- 61
2.6.5 The TWOACK and S-TWOACK Schemes --------------------------------------- 62
CHAPTER 3 MOTIVATIONS AND ASSUMPTIONS ----------------------------------------- 63
3.1 LIMITATION OF THE EXISTING MONITORING SCHEME ----------------------------- 63
3.2 MONITORING ELEMENTS ------------------------------------------------------ 65
3.2 ASSUMPTIONS -------------------------------------------------------------- 66
CHAPTER 4 ROUTING MISBEHAVIOR DETECTION --------------------------------------- 68
4.1 OUTLINE OF THE PROPOSED FRAMEWORK ---------------------------------------- 69
4.2 COLLECTION OF INFORMATION ON NEIGHBOR NODES ------------------------------ 71
4.2.1 Neighbor List Construction for the Static Networks -------------------- 71
4.2.2 Discussions ----------------------------------------------------------- 76
4.2.3 Neighbor List Construction for the Dynamic Networks ------------------- 78
4.3 MONITORING THE NETWORK TRAFFIC ------------------------------------------- 81
4.4 MISBEHAVIOR DETECTION PROCESS -------------------------------------------- 84
4.4.1 Representative Node Selection ----------------------------------------- 85
4.4.2 Misbehavior Decision -------------------------------------------------- 86
4.5 REVISING THRESHOLD AUTOMATICALLY ----------------------------------------- 87
4.6 SUMMARY ------------------------------------------------------------------ 88
CHAPTER 5 EXPERIMENTAL RESULTS ------------------------------------------------ 90
5.1 ENVIRONMENT OF EXPERIMENT ------------------------------------------------ 90
5.2 RESULTS OF EXPERIMENT ON DETECTION PERFORMANCE --------------------------- 91
5.3 EXPERIMENTAL RESULTS ON NETWORK PERFORMANCE ------------------------------ 95
CHAPTER 6 COLLUSION-BASED ROUTING MISBEHAVIOR DETECTION ----------------------- 96
6.1 RELATED WORKS ------------------------------------------------------------ 97
6.1.1 Wormhole Attacks ------------------------------------------------------ 97
6.1.2 Previous Wormhole Attack Detection Methods ---------------------------- 99
6.2 WORMHOLE ATTACK DEFENSE MECHANISM ---------------------------------------- 102
6.2.1 Indication of the Wormhole Attacks ------------------------------------ 102
6.2.2 Building a Neighbor List ---------------------------------------------- 105
6.2.3 Detecting Wormhole ---------------------------------------------------- 106
6.2.4 Responding to Wormhole ------------------------------------------------ 107
6.3 ANALYSIS OF THE PROPOSED PROTOCOL ---------------------------------------- 109
6.3.1 Security Analysis ----------------------------------------------------- 109
6.3.2 Performance Analysis -------------------------------------------------- 110
6.4 SIMULATION --------------------------------------------------------------- 111
6.5 SUMMARY ------------------------------------------------------------------ 113
CHAPTER 7 CONCLUSIONS -------------------------------------------------------- 114
BIBLIOGRAPHY ------------------------------------------------------------------ 116|FIGURE 1. ROUTE INFECTION RATIO UNDER ROUTING MISBEHAVIOR ATTACK ------------------------------ 6
FIGURE 2. NETWORK PERFORMANCE DEGRADATION UNDER CASE A ATTACK --------------------------------- 7
FIGURE 3. NETWORK PERFORMANCE DEGRADATION UNDER CASE B ATTACK --------------------------------- 7
FIGURE 4. AN EXAMPLE OF SYBIL ATTACK ---------------------------------------------------------- 21
FIGURE 5. AN EXAMPLE SENSOR NETWORK UNDER SELECTIVE FORWARDING ATTACKS ------------------------ 27
FIGURE 6. THE TYPES OF SELECTIVE FORWARDING ATTACKS ------------------------------------------- 28
FIGURE 7. NETWORK TRAFFIC INFORMATION MONITORING METHOD USING COOPERATING NODES --------------- 70
FIGURE 8. THE PROCESS OF CREATING A 1-HOP NEIGHBOR NODE INFORMATION LIST ---------------------- 72
FIGURE 9. THE PROCESS OF CREATING A 2-HOP NEIGHBOR NODE INFORMATION LIST ---------------------- 72
FIGURE 10. AN EXAMPLE OF A NEIGHBOR NODE INFORMATION LIST ------------------------------------- 76
FIGURE 11. THE SCHEMATIC VIEW OF THE NEIGHBOR LIST DISTRIBUTION IN THE DYNAMIC NETWORKS ------- 79
FIGURE 12. AN EXAMPLE OF MONITORING MESSAGES PROCESSED BY A NODE ------------------------------ 82
FIGURE 13. AN EXAMPLE OF MONITORING PROCESS FOR A NODE ---------------------------------------- 84
FIGURE 14. ADJUSTING THRESHOLD VALUE ---------------------------------------------------------- 87
FIGURE 15. CHANGE IN THE INTRUSION DETECTION RATE --------------------------------------------- 91
FIGURE 16. THE CUMULATIVE NUMBER OF DROPPED PACKETS ACCORDING TO SIMULATION TIME -------------- 92
FIGURE 17. CHANGE IN THE PACKET LOSS RATE ACCORDING TO THE NUMBER OF ATTACKERS ---------------- 93
FIGURE 18. THE EFFECTS OF THE TIME INTERVAL DURING NEIGHBOR LIST CONSTRUCTION ----------------- 94
FIGURE 19. CHANGE IN THE AVERAGE NETWORK DELAY ACCORDING TO THE NUMBER OF ATTACKERS ----------- 94
FIGURE 20. THE NUMBER OF MESSAGES EXCHANGED DURING THE NEIGHBOR NODE LIST CONSTRUCTION -------- 95
FIGURE 21. AN EXAMPLE OF WORMHOLE ATTACK ------------------------------------------------------ 98
FIGURE 22. AN EXAMPLE OF THE PACKET INCLUDING IDENTITIES AND MACS ----------------------------- 107
FIGURE 23. CUMULATIVE NUMBER OF DROPPED PACKET BY ATTACKER ------------------------------------ 111
FIGURE 24. AVERAGE LATENCY DURING SIMULATION TIME --------------------------------------------- 112
FIGURE 25. PACKET LOSS RATIO OF BOTH WITHOUT AND WITH DEFENSE MECHANISM ----------------------- 113|TABLE 1. ATTACK TREE ---------------------------------------------------------- 4
TABLE 2. SIMULATION PARAMETERS ------------------------------------------------ 5
TABLE 3. A SUMMARY OF TIARA COUNTERMEASURES AGAINST INTRUSION ATTACKS --------- 52
TABLE 4. THE NEIGHBOR LIST CONSTRUCTION ALGORITHM FOR THE DYNAMIC NETWORKS ---- 81
TABLE 5. MONITORING ALGORITHM WHEN NODE X FORWARDS A PACKET TO NODE W --------- 83
TABLE 6. MONITORING ALGORITHM WHEN NODE X RECEIVES A PACKET FROM NODE W ------- 83
TABLE 7. SIMULATION PARAMETERS ------------------------------------------------ 90
TABLE 8. THE RESULTS OF THE NEIGHBOR CORRECTNESS TEST ------------------------- 108MasterA wireless ad hoc network has an autonomous structure in which network nodes scattered around without the help of specific infrastructure communicate and cooperate with one another through wireless media. In a wireless ad hoc network, all the nodes perform a series of routing processes during communication and deliver messages to the final destination. That is, for a message to be transmitted from the original sender to the final destination, multiple nodes repeat the process of receiving the message from the previous node and sending it to the next node. Accordingly, if one of the nodes misbehaves during the message transmission delivery process, communication cannot be made properly. Misbehavior is an intentional damage to the network by not following the routing process and by causing the loss of messages. Most of misbehaviors bring damages such as denial of service to the network. For example, if all packets to be delivered by a malicious node disguised as a normal node are discarded, all communication sessions that use a route including the node cannot get service. This type of attacks includes black hole, gray hole (selective forwarding), wormhole, message blocking, and message delivery to a wrong path.
Such attacks are detected by the method of network monitoring that watches continuously whether messages are delivered properly to the next hop. This method basically uses watchdog. Watchdog observes through overhearing, which is a characteristic of communication technology based on wireless media, whether the node at the next hop delivers the message, which has been passed by the watchdog to the hop, to its next hop accurately. However, the use of watchdog has the difficulty that each message transmission has to be overheard continuously. Furthermore, it should have information on all messages transmitted. There are also technical limitations in watchdog itself.
Thus, in this study, we reviewed problems in previous researches, and as a solution for the problems, proposed a new monitoring method that does not use overhearing watchdog. The proposed method can detect attacks in a more effective way while solving problems in the existing watchdog method. In the proposed method, each node accumulates statistical data on messages that it has processed in the communication process. Based on information accumulated in itself and neighbor nodes to be monitored, each node determines whether a neighbor node under monitoring is normal or damaging the network through frequent wrong routing behaviors. An experiment using a network simulator showed that the proposed method is more efficient than other existing methods.
Wormhole attack is one of the most severe threats to ad hoc networks. There have been many researches to overcome the wormhole attack. These researches, however, still have some limitations to handle wormhole attacks properly such as burden of computation, complicated pre-work for each communication, and no defense method. In this study, we propose an effective wormhole attack defense mechanism that can properly detect wormhole attacks and respond to them. Each node maintains its neighbors’ information. According to the information, each node can identify replayed packet. We analyze the effectiveness of the proposed method and the efficiency of the approach by using traffic and memory space measure
Centralized Contention Based MAC for OFDMA WLAN
Full text linkThe IEEE 802.11 wireless local area network (WLAN) is the most widely deployed communication standard in the world. Currently, the IEEE 802.11ax draft standard is one of the most advanced and promising among future wireless network standards. However, the suggested uplink-OFDMA (UL-OFDMA) random access method, based on trigger frame-random access (TF-R) from task group ax (TGax), does not yet show satisfying system performance. To enhance the UL-OF DMA capability of the IEEE 802.11ax draft standard, we propose a centralized contention-based MAC (CC-MAC) and describe its detailed operation. In this paper, we analyze the performance of CC-MAC by solving theMarkov chain model and evaluating BSS throughput compared to other methods, such as DCF and TF-R, by computer simulation. Our results show that CC-MAC is a scalable and efficient scheme for improving the system performance in a UL-OFDMA random access situation in IEEE 802.11ax.112Ysciescopu
Reduction of highly bulky triphenolamine molybdenum nitrido and chloride complexes
No full textTransition metal nitrides are key intermediates in the catalytic reduction of dinitrogen to ammonia. To date, transition metal nitride complexes with the triphenolamine (TPA) ligand have not been reported and the system with the ligand has been much less studied for ammonia formation compared with other systems. Herein, we report a series of molybdenum complexes supported by a sterically demanding TPA ligand, including a nitrido complex N=Mo(TPA). We achieved the stoichiometric conversion of the nitride moiety into ammonia under ambient conditions by adding proton and electron sources to N Mo(TPA). However, the catalytic turnover for N-2 reduction to ammonia was not observed in the triphenolamine ligand system unlike the Schrock system-triamido-amine ligand. Density functional theory calculation revealed that the molybdenum center favors binding NH3 over N-2 by 16.9 kcal mol(-1) and the structural lability of the trigonal bipyramidal (TBP) molybdenum complex seems to prevent catalytic turnover. Our systematic study showed that the electronegativity and bond length of ancillary ligands determine the preference between N-2 and NH3, suggesting a systematic design strategy for improvement.11Nsciescopu
Fixation of Dinitrogen at an Asymmetric Binuclear Titanium Complex
No full textA new type of dititanium dinitrogen complex supported by a triphenolamine (TPA) ligand is reported. Analysis by single-crystal X-ray diffraction and Raman and NMR spectroscopy reveals different coordination geometries for the two titanium centers. Hence, coordination of TPA and a nitrogen ligand results in trigonal-bipyramidal geometry, while an octahedral titanium center is obtained upon additional coordination of an ethoxide generated upon C-O bond cleavage in a diethyl ether solvent molecule. The titanium complex successfully generates ammonia in the presence of an excess amount of PCy3HI and KC8 in 154% yield (per titanium atom). A titanium complex with a bulkier TPA does not form a dinitrogen complex, and mononuclear titanium dinitrogen complexes were not accessible, presumably because of the high tendency of early transition metals to form binuclear dinitrogen complexes.11Nsciescopu
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Dispelling the Myths Behind First-author Citation Counts
Full text linkWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
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