• Journal of KIISE:Information Networking
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• v.32 no.4
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• pp.452-461
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• 2005

In the star VPN (Virtual Private Network) topology, the traffic between the communicating two CPE(Customer Premise Equipment) VPN GW(Gateway)s nay be inefficiently transferred. Also, the Center VPN GW nav erperience the overload due to excessive packet processing overhead. As a solution to this problem, a direct tunnel can be established between the communicating two CPE VPN GWs using the IKE (Internet Key Exchange) mechanism of IPSec(IP Security). In this case, however, the tunnel establishment and management nay be complicated. In this paper, we propose a mechanism called' SVOT (Star VPN On-demand Tunnel)', which automatically establishes a direct tunnel between the communicating CPE VPN GWs based on demand. In the SVOT scheme, CPE VPN GWs determine whether it will establish a direct tunnel or not depending on the traffic information monitored. CPE VPN GW requests the information that is necessary to establishes a direct tunnel to the Center VPN GW Through a simulation, we investigate the performance of the scheme performs better than the SYST scheme with respect to scalability, traffic efficiency and overhead of Center VPN GW, while it shows similar performance to the FVST with respect to end-to-end delay and throughput.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.43 no.7 s.349
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• pp.50-59
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• 2006

The new communication paradigm is rapidly shifted from wireless mobile networks to an All-IP(Internet Protocol) network, led by service industry leaders and communication manufacturers. In this paradigm, providing authentication and session keys of a subscriber becomes one of the critical tasks because of IP open accessibility among heterogeneous networks. In this paper, we introduce authentication process procedure of heterogeneous wireless mobile networks and develop so-called IMAS(Integrated Mobile Authentication Server) which can securely inter-work among all mobile networks and support the legacy networks with backward compatibility. Especially, in designing IMAS, mobile authentication inter-working mechanism, key management technique, and other issues to be overcome are presented. We analyze and evaluate the performance of authentication algorithm which creates session key. A simulation environment of IMAS is established, and a performance(TPS; Transaction Per Second) result is analyzed and evaluated. It turned out that IMAS works among heterogeneous wireless mobile networks without compensating efficiency and functionalities of the legacy networks and decrease the entropy of data redundancy and data inconsistency among networks because of the integrity of the distributed Data Base(DB).

• The KIPS Transactions:PartC
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• v.12C no.6 s.102
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• pp.855-864
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• 2005

In this paper, we propose an intrusion detection system(IDS) architecture which can detect and respond against the generation of abnormal traffic such as malicious code and Internet worms. We model the system, design and implement a simulator using OPNET Modeller, for the performance analysis on the response capacity of alert information in the proposed system. At first, we model the arrival process of alert information resulted from abnormal traffic. In order to model the situation in which alert information is intensively produced, we apply the IBP(Interrupted Bernoulli Process) which may represent well the burstiness of traffic. Then we perform the simulation in order to gain some quantitative understanding of the system for our performance parameters. Based on the results of the performance analysis, we analyze factors which may hinder in accelerating the speed of security node, and would like to present some methods to enhance performance.

• Journal of the Korea Society for Simulation
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• v.19 no.4
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• pp.151-159
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• 2010

Currently, by using the Internet, We can do varius things such as Web surfing, email, on-line shopping, stock trading on your home or office. However, as being out of the concept of security from the beginning, it is the big social issues that malicious user intrudes into the system through the network, on purpose to steal personal information or to paralyze system. In addition, network intrusion by ordinary people using network attack tools is bringing about big worries, so that the need for effective and powerful intrusion detection system becomes very important issue in our Internet environment. However, it is very difficult to prevent this attack perfectly. In this paper we proposed the algorithm for the detection of DoS attacks, and developed attack detection tools. Through learning in a normal state on Step 1, we calculate thresholds, the number of packets that are coming to each port, the median and the average utilization of each port on Step 2. And we propose values to determine how to attack detection on Step 3. By programing proposed attack detection algorithm and by testing the results, we can see that the difference between the median of packet mounts for unit interval and the average utilization of each port number is effective in detecting attacks. Also, without the need to look into the network data, we can easily be implemented by only using the number of packets to detect attacks.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.36 no.11B
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• pp.1297-1304
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• 2011

SIP(Session Initiation Protocol) has some security vulnerability because it works on the Internet. Therefore, the proxy server can be affected by the flooding attack such as DoS and service interruption. However, traditional schemes to corresponding Denial of Service attacks have some limitation. These schemes have high complexity and cannot protect to the variety of Denial of Service attack. In this paper, we newly define the normal user who makes a normal session observed by verifier module. Our method provides continuous service to the normal users in the various situations of Denial of Service attack as constructing a whitelist using normal user information. Various types of attack/normal traffic are modeled by using OPNET simulator to verify our scheme. The simulation results show that our proposed scheme can prevent DoS attack and achieve a low false rate and fast searching time.

• The Journal of Korean Association of Computer Education
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• v.13 no.1
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• pp.53-64
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• 2010

In this paper, we tried to enable a mobile device as a resource to access to mobile grid networks. By advanced Internet techniques, the use of mobile devices has been rapidly increased. Some researches in mobile grid computing tried to combine grid computing with mobile devices. However, according to intrinsic properties of mobile environments, mobile devices have many considerations, such as mobility management, disconnected operation, device heterogeneity, service discovery, resource sharing, security, and so on. To solve these problems, there are two trends for mobile grid computing: a proxy-based mobile grid architecture and an agent-based mobile grid architecture. We focus on a proxy-based mobile grid architecture with IP-paging, which can easily manage idle mobile devices and grid resource status information. Also, we use SIP(Session Initiation Protocol)to support mobility management, mobile grid services. We manage variation of mobile device state and power by paging cache. Finally, using the candidate set and the reservation set of resources, we perform task migration. The performance evaluation by simulation, shows improvement of efficiency and stability during execution.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.14 no.6
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• pp.1416-1422
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• 2010

Various other platforms have appeared due to the abolishment of WIPI requirement and increased problems related with hacking and security. Since levels consisting of these platforms are composed of various APIs (Application Programming Interfaces) which are not standardized, other ways must be considered to protect data which are transferred using XML formats. Therefore, XML encryption API and XML digital signature API for data protection and certification, which are both responsible to define mark-up languages for XML encryption and digital signature respectively, were designed in this paper. The simulation system which played the role of the server and client between two terminal units was realized to validate the APIs.

• The KIPS Transactions:PartC
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• v.11C no.6 s.95
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• pp.747-754
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• 2004

Today, wireless LANs are widely deployed in various places such as corporate office conference rooms, industrial warehouses, Internet-ready classrooms, etc. However, new concerns have been raised regarding suity. Currently, both virtual private network(VPN) and WEP are used together as a strong authentication mechanism. While security is increased by using VPN and WEP together, unnecessary redundancy occurs causing power consumption increase and authentication speed decrease in the authentication process. In this paper a new synchronization protocol for authentication is proposed which allows simple authentication, minimal power consumption at the mobile station, and high utilization of authentication stream. This is achieved by using one bit per a frame authentication, while main authentication process including synchronization is handled by access points. Computer simulation reveals that the proposed scheme significantly improves the authentication efficiency in terms of the number of authenticated frames and authentication speed compared with an earlier protocol employing a similar authentication approach.

• Journal of Convergence for Information Technology
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• v.10 no.7
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• pp.41-48
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• 2020

Recently, the spreading business of AMI (Advanced Metering Infrastructure) remote metering systems in various regions of the country has been activated, and it provides various metering functions such as two-way communication and security plan functions for power demand management. Current AMI system is difficult to analyze based on the existing RDB(Relational Database) due to the increase in the size of new internal IoT devices and networks. This study proposes a new GDB(Graph Database) based failure analysis method that utilizes existing RDB data. It analyzes the correlation of new failure patterns through accumulated data such as internal thresholds and status values. As a result of GDB-based simulation, it was confirmed that RDB can predict to a new obstacle pattern that was difficult to analyze.

• Journal of the Institute of Electronics Engineers of Korea CI
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• v.47 no.5
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• pp.67-74
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• 2010

Recently, the early detection and prevention of worm research is mainly studying based on the analysis of generalized worm propagation property. However, it is not easy to do Worm early detection with its attributes because the modeling method for Worm propagation is vague and not specified yet. Worm scanning method is exceedingly effect to Worm propagation process. This paper describes a modeling method and its simulations to estimate various worm growth patterns and their corresponding propagation algorithms. It also tests and varies the impact of various improvements, starting from a trivial simulation of worm propagation and the underlying network infrastructure. It attempts to determine the theoretical maximum propagation speed of worms and how it can be achieved. Moreover, we present the feasibility of the proposed model based on real testbed for verification.