Sürdürülebilir Yeşil Kampüs Koleksiyonu / Sustainable Green Campus Collection
Permanent URI for this collectionhttps://hdl.handle.net/11147/7755
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Master Thesis Intrusion Detection System Alert Correlation With Operating System Level Logs(Izmir Institute of Technology, 2009) Toprak, Mustafa; Aytaç, İsmail Sıtkı; Toprak, Mustafa; Aytaç, İsmail Sıtkı; 03.04. Department of Computer Engineering; 03. Faculty of Engineering; 01. Izmir Institute of TechnologyInternet is a global public network. More and more people are getting connected to the Internet every day to take advantage of the Internetwork connectivity. It also brings in a lot of risk on the Internet because there are both harmless and harmful users on the Internet. While an organization makes its information system available to harmless Internet users, at the same time the information is available to the malicious users as well. Most organizations deploy firewalls to protect their private network from the public network. But, no network can be hundred percent secured. This is because; the connectivity requires some kind of access to be granted on the internal systems to Internet users. The firewall provides security by allowing only specific services through it. The firewall implements defined rules to each packet reaching to its network interface. The IDS complements the firewall security by detected if someone tries to break in through the firewall or manages to break in the firewall security and tried to have access on any system in the trusted site and alerted the system administrator in case there is a breach in security. However, at present, IDSs suffer from several limitations. To address these limitations and learn network security threats, it is necessary to perform alert correlation. Alert correlation focuses on discovering various relationships between individual alerts. Intrusion alert correlation techniques correlate alerts into meaningful groups or attack scenarios for ease to understand by human analysts. In order to be sure about the alert correlation working properly, this thesis proposed to use attack scenarios by correlating alerts on the basis of prerequisites and consequences of intrusions. The architecture of the experimental environment based on the prerequisites and consequences of different types of attacks, the proposed approach correlates alerts by matching the consequence of some previous alerts and the prerequisite of some later ones with OS-level logs. As a result, the accuracy of the proposed method and its advantage demonstrated to focus on building IDS alert correlation with OS-level logs in information security systems.Master Thesis A Firewall Design for Academic Environments(Izmir Institute of Technology, 2001) Tok, Metin; Koltuksuz, Ahmet; Koltuksuz, Ahmet Hasan; 03.04. Department of Computer Engineering; 03. Faculty of Engineering; 01. Izmir Institute of TechnologyComputer networks in academic environments could have many secUlity problems if there weren't enough precaution. The source of these problems is generally vulnerabilities of TCP/IP protocol and Internet. Vulnerabilities can cause threats. These threats will be analyzed in this thesis. There are many kind of countelmeasures to prevent the assets of the academic networks. Firewalls are a kind of countermeasure against these attacks. In this thesis, these countelmeasures will be also analyzed and a firewall will be designed and proposed for academic environments against these threats.Master Thesis Time synchronization in wireless sensor metworks(Izmir Institute of Technology, 2008) Kulaklı, Ali Burak; Aytaç, İsmail Sıtkı; Aytaç, İsmail Sıtkı; 03.04. Department of Computer Engineering; 03. Faculty of Engineering; 01. Izmir Institute of TechnologyIn this thesis, an enhanced synchronization algorithm for Wireless Sensor Networks is proposed. This algorithm uses TPSN (Timing-sync protocol for sensor networks) as a base synchronizer and does modifications on it to achieve a better synchronization with a lower message overhead. Basically, there are three improvements that can be applied onto TPSN, which are clustering the network, chain synchronization among nodes and adaptive synchronization interval. In the first phase of the thesis, a simulation environment is provided for TPSN using pthreads on a Linux computer. This environment helps understanding the parameters that TPSN relies on and testing the algorithm in different simulated environments with different characteristics using the enhancements onto TPSN algorithm. In the second phase, ns2 simulator environment is used to get more precise results and test the modifications. Finally, latest modifications are done on TPSN and all the results are gathered from ns2.Master Thesis Access Monitoring System for Distributed Firewall Policies(Izmir Institute of Technology, 2008) Çakı, Oğuzhan; Tuğlular, Tuğkan; Tuğlular, Tuğkan; 03.04. Department of Computer Engineering; 03. Faculty of Engineering; 01. Izmir Institute of TechnologyInternet has provided several benefits in terms of information sharing. However, Internet is an insecure environment that can cause threats to private networks. As a result, network security becomes a critical issue. One of the important tools used in network security is firewall. Firewalls protect a private network from external threats by restricting network traffic according to predefined security rules. Basically, firewalls apply these rules to each packet that passes over them. Distributed firewalls are a new approach to firewall to overcome some drawbacks of traditional firewalls. Distributed firewall design is based on the idea of enforcing the policy rules at the endpoints rather than a single entry point to network. Management of policy rules is a critical issue in both traditional and distributed firewalls. We propose a monitoring application for distributed firewall policies to keep track of actions (create, read. update, delete) performed on policy rule set. The resulting data produced by the monitoring application will be very helpful in policy management process.Master Thesis A Cluster Based Communication Architecture for Distributed Applications in Mobile Ad Hoc Networks(Izmir Institute of Technology, 2006) Dağdeviren, Orhan; Erciyeş, Kayhan; Dağdeviren, Orhan; Erciyes, Kayhan; 03.04. Department of Computer Engineering; 03. Faculty of Engineering; 01. Izmir Institute of TechnologyIn this thesis, we aim to design and implement three protocols on a hierarchical architecture to solve the balanced clustering, backbone formation and distributed mutual exclusion problems for mobile ad hoc network(MANET)s. Our ¯rst goal is to cluster the MANET into balanced partitions. Clustering is a widely used approach to ease implemen-tation of various problems such as routing and resource management in MANETs. We propose the Merging Clustering Algorithm(MCA) for clustering in MANETs that merges clusters to form higher level of clusters by increasing their levels. Secondly, we aim to con-struct a directed ring topology across clusterheads which were selected by MCA. Lastly, we implement the distributed mutual exclusion algorithm based on Ricart-Agrawala algo-rithm for MANETs(Mobile RA). Each cluster is represented by a coordinator node on the ring which implements distributed mutual exclusion algorithm on behalf of any member in the cluster it represents. We show the operations of the algorithms, analyze their time and message complexities and provide results in the simulation environment of ns2.Master Thesis End-To Security for Mobile Devices(Izmir Institute of Technology, 2004) Kayayurt, Barış; Tuğlular, Tuğkan; Tuğlular, Tuğkan; Tuğlular, Tuğkan; 03.04. Department of Computer Engineering; 03. Faculty of Engineering; 01. Izmir Institute of TechnologyEnd-to-end security has been an emerging need for mobile devices with the widespread use of personal digital assistants and mobile phones. Transport Layer Security Protocol (TLS) is an end-to-end security protocol that is commonly used in Internet, together with its predecessor, SSL protocol. By using TLS protocol in mobile world, the advantage of the proven security model of this protocol can be taken.J2ME (Java 2 Micro Edition) has been the de facto application platform used in mobile devices. This thesis aims to provide an end-to-end security protocol implementation based on TLS 1.0 specification and that can run on J2ME MIDP (Mobile Information Device Profile) environment. Because of the resource intensive public-key operations used in TLS, this protocol needs high resources and has low performance. Another motivation for the thesis is to adapt the protocol for mobile environment and to show that it is possible to use the protocol implementation in both client and server modes. An alternative serialization mechanism is used instead of the standard Java object serialization that is lacking in MIDP. In this architecture, XML is used to transmit object data.The mobile end-to-end security protocol has the main design issues of maintainability and extensibility. Cryptographic operations are performed with a free library, Bouncy Castle Cryptography Package. The object-oriented architecture of the protocol implementation makes the replacement of this library with another cryptography package easier.Mobile end-to-end security protocol is tested with a mobile hospital reservation system application. Test cases are prepared to measure the performance of the protocol implementation with different cipher suites and platforms. Measured values of all handshake operation and defined time spans are given in tables and compared with graphs.Master Thesis Development of a Distributed Firewall Administration Tool(Izmir Institute of Technology, 2008) Erdoğan, Yunus; Tuğlular, Tuğkan; Tuğlular, Tuğkan; 03.04. Department of Computer Engineering; 03. Faculty of Engineering; 01. Izmir Institute of TechnologyToday firewalls not only guard internal computer networks but also individual personal computers against malicious and unauthorized accesses from outside. The purpose of this study is to create architecture and its corresponding application to manage distributed firewalls running on Microsoft Windows platform. Distributed Firewall Administration is about creating a management center for a network composed of the firewalls running on Microsoft Windows platform. Main important part of this work is to determine distributed firewall network topology with breadth-first search and depth-first search algorithms.The Microsoft Windows Firewall API makes it possible to programmatically manage the features of firewalls running on windows platform by allowing applications to create, enable and disable firewall exceptions. This study used the Windows Firewall API to manage the features of it. This API is only reachable using C/C++ low level programming languages.Distributed Firewall Administration Tool (DFAT) can add, modify or delete rules on the end-user firewall rule set, these rules stored on the database. This tool works on a distributed environment, there is a parent child relationship between firewalls. Parent firewalls have right to manage its child firewall.s rule set. Firewalls introduce themselves to each other with broadcast method.Master Thesis A Dominating Set Based Communication Architecture for Distributed Applications in Mobile Ad Hoc Networks(Izmir Institute of Technology, 2007) Çokuslu, Deniz; Çokuslu, Deniz; Aytaç, İsmail Sıtkı; Aytaç, İsmail Sıtkı; 03.04. Department of Computer Engineering; 03. Faculty of Engineering; 01. Izmir Institute of TechnologyIn this thesis, we aim to design and implement algorithms in a distributed environment in order to solve clustering, backbone formation and efficient routing problems for mobile ad hoc networks(MANET)s. Our first goal is to find a connected dominating set (CDS), then construct clusters using the clusterhead information and extend this approach to multi-level clusters. We propose a new Connected Dominating Set based clustering algorithm for clustering in MANETs. Our algorithm is based on Wu and Li's algorithm, however we provide significant modifications and heuristics such as considering the degrees of the nodes during marking process. We also extend our algorithm in order to generate a hierarchy of clusters. Our second goal is to implement a flooding based routing mechanism on top of CDS based clusters. We propose a two level flooding mechanism by using the CDS members as the gateways of the clusters. We describe the algorithms, analyze their time and message complexities and measure their performance in the simulation environments.Master Thesis An Analysis of Key Generation Efficiency of Rsa Cryptosystem in Distributed Environments(Izmir Institute of Technology, 2005) Çağrıcı, Gökhan; Koltuksuz, Ahmet; Koltuksuz, Ahmet Hasan; 03.04. Department of Computer Engineering; 03. Faculty of Engineering; 01. Izmir Institute of TechnologyAs the size of the communication through networks and especially through Internet grew, there became a huge need for securing these connections. The symmetric and asymmetric cryptosystems formed a good complementary approach for providing this security. While the asymmetric cryptosystems were a perfect solution for the distribution of the keys used by the communicating parties, they were very slow for the actual encryption and decryption of the data flowing between them. Therefore, the symmetric cryptosystems perfectly filled this space and were used for the encryption and decryption process once the session keys had been exchanged securely. Parallelism is a hot research topic area in many different fields and being used to deal with problems whose solutions take a considerable amount of time. Cryptography is no exception and, computer scientists have discovered that parallelism could certainly be used for making the algorithms for asymmetric cryptosystems go faster and the experimental results have shown a good promise so far. This thesis is based on the parallelization of a famous public-key algorithm, namely RSA.Master Thesis Firewall monitoring using intrusion detection systems(Izmir Institute of Technology, 2005) Asarcıklı, Şükran; Tuğlular, Tuğkan; Tuğlular, Tuğkan; 03.04. Department of Computer Engineering; 03. Faculty of Engineering; 01. Izmir Institute of TechnologyMost organizations have intranet, they know the benefits of connecting their private LAN to the Internet. However, Internet is inherently an insecure network. That makes the security of the computer systems an imported problem. The first step of network security is firewalls. Firewalls are used to protect internal networks from external attacks through restricting network access according to the rules. The firewall must apply previously defined rules to each packet reaching to its network interface. If the application of rules are prohibited due to malfunction or hacking, internal network may be open to attacks and this situation should be recovered as fast as possible. In order to be sure about the firewall working properly, we proposed to use Intrusion Detection Systems (IDS)to monitor firewall operation. The architecture of our experimental environment is composed of a firewall and two IDSs. One IDS is between external network and firewall, while the other is between firewall and private network. Those two IDSs are invisible to the both networks and they send their information to a monitoring server, which decides, based on two observations, whether the firewall is working properly or not.