Mehmet Hadi Gunes

Resolving IP aliases in building traceroute-based internet maps

Alias resolution, the task of identifying IP addresses belonging to the same router, is an important step in building traceroute-based Internet topology maps. Inaccuracies in alias resolution affect the representativeness of constructed topology maps. This in turn affects the conclusions derived from studies that use these maps. This paper presents two complementary studies on alias resolution. First, we present an experimental study to demonstrate the impact of alias resolution on topology measurement studies. Then, we introduce an alias resolution approach called analytic and probe-based alias resolver (APAR). APAR consists of an analytical component and a probe-based component. Given a set of path traces, the analytical component utilizes the common IP address assignment scheme to infer IP aliases. The probe-based component introduces a minimal probing overhead to improve the accuracy of APAR. Compared to the existing state-of-the-art tool ally, APAR uses an orthogonal approach to resolve a large number of IP aliases that ally fails to identify. Our extensive verification study on sample data sets shows that our approach is effective in resolving many aliases with good accuracy. Our evaluations also indicate that the two approaches (ally and APAR) should be used together to maximize the success of the alias resolution process.

Analytical IP Alias Resolution

IP alias resolution is an important step in generating sample Internet topologies from collected path traces. Inaccuracies in IP alias resolution may significantly affect the characteristics of the resulting sample topologies. This in turn affects the accuracy of measurement results obtained using such topologies. Existing tools for alias resolution use an active probing approach. They induce significant traffic overhead into the network and critically depend on the participation of the routers. Recent studies have reported on the limited effectiveness of these approaches [1], [2]. In this paper, we present a novel approach, called Analytical Alias Resolver (AAR), for IP alias resolution. Given a set of path traces, AAR utilizes the common IP address assignment scheme to infer IP aliases from the collected path traces. AAR does not incur traffic overhead due to active probing for alias resolution. Our experimental evaluations on a set of collected Internet path traces show that, compared to existing approaches, AAR can detect significantly more number of IP aliases.

Ensuring access control in cloud provisioned healthcare systems

An important issues in cloud provisioned multi-tenant healthcare systems is the access control, which focuses on the protection of information against unauthorized access. As different tenants including hospitals, clinics, insurance companies, and pharmacies access the system, sensitive information should be provided only to authorized users and tenants. In this paper, we analyze the requirements of access control for healthcare multi-tenant cloud systems and propose to adapt Task-Role Based Access Control with constraints such as least privilege, separation of duty, delegation of tasks, and spatial and temporal access.

Friend recommendations in social networks using genetic algorithms and network topology

Social networking sites employ recommendation systems in contribution to providing better user experiences. The complexity in developing recommendation systems is largely due to the heterogeneous nature of social networks. This paper presents an approach to friend recommendation systems by using complex network theory, cognitive theory and a Pareto-optimal genetic algorithm in a two-step approach to provide quality, friend recommendations while simultaneously determining an individuals perception of friendship. Our research emphasizes that by combining network topology and genetic algorithms, better recommendations can be achieved compared to each individual counterpart. We test our approach on 1,200 Facebook users in which we observe the combined method to outper form purely social or purely network-based approaches. Our preliminary results represent strong potential for developing link recommendation systems using this combined approach of personal interests and the underlying network.

Importance of IP Alias Resolution in Sampling Internet Topologies

Internet measurement studies utilize traceroute-based path traces to build representative Internet maps. These maps are then used to analyze various topological characteristics of the Internet. IP alias resolution is an important step in building a map from a set of collected path traces. In this paper, we study the impact of incomplete IP alias resolution on Internet measurement studies. Using a set of synthetic topologies and a genuine topology map, we experimentally show that the accuracy/completeness of alias resolution has an important effect on the observed topological characteristics. The results obtained in this work point out the importance of IP alias resolution and call for further research in alias resolution.

Inferring subnets in router-level topology collection studies

Internet measurement studies require availability of representative topology maps. Depending on the map resolution (e.g., autonomous system level or router level), the procedure of collecting and processing an Internet topology map involves different tasks. In this paper, we present a new task, i.e., subnet inference, to advance the current state of the art in topology collection studies. Utilizing a technique to infer the subnet relations among the routers in the resulting topology map, we identify IP addresses that are connected over the same connection medium. We believe that the successful inclusion of subnet relations among the routers will yield topology maps that are closer, at the network layer, to the sampled segments of the Internet in router level topology measurement studies.

Analyzing Router Responsiveness to Active Measurement Probes

Active probing has increasingly been used to collect information about the topological and functional characteristics of the Internet. Given the need for active probing and the lack of a widely accepted mechanism to minimize the overhead of such probes, the traffic and processing overhead introduced on the routers are believed to become an important issue for network operators. In this paper, we conduct an experimental study to understand the responsiveness of routers to active probing both from a historical perspective and current practices. One main finding is that network operators are increasingly configuring their devices not to respond to active direct probes. In addition, ICMP based probes seem to elicit most responses and UDP based probes elicit the least.

Secure communications in the smart grid

This paper focuses on deployment of smart meters in the power distribution systems to enhance the operation infrastructure. An important challenge in establishing a communication paradigm between the utilities and the customers is that customers are susceptible to privacy concerns. In this paper, we present a model to ensure the privacy and integrity of communicating parties within the smart grid by using smart meters as a gateway between intra- and inter-network communications. In particular, we utilize the smart meter as a firewall to manage incoming and outgoing traffic and mediate household devices based on the instructions from the electric utility. Moreover, third parties are introduced in our model such as service providers so that they can monitor and manage the contracted customers by using the existing communication infrastructure.

Review: An overview of anonymity technology usage

Anonymity technologies enable Internet users to maintain a level of privacy that prevents the collection of identifying information such as the IP address. Understanding the deployment of anonymity technologies on the Internet is important to analyze the current and future trends. In this paper, we provide a tutorial survey and a measurement study to understand the anonymity technology usage on the Internet from multiple perspectives and platforms. First, we review currently utilized anonymity technologies and assess their usage levels. For this, we cover deployed contemporary anonymity technologies including proxy servers, remailers, JAP, I2P, and Tor with the geo-location of deployed servers. Among these systems, proxy servers, Tor and I2P are actively used, while remailers and JAP have minimal usage. Then, we analyze application-level protocol usage and anonymity technology usage with different applications. For this, we preform a measurement study by collecting data from a Tor exit node, a P2P client, a large campus network, a departmental email server, and publicly available data on spam sources to assess the utilization of anonymizer technologies from various perspectives. Our results confirm previous findings regarding application usage and server geo-location distribution where certain countries utilize anonymity networks significantly more than others. Moreover, our application analysis reveals that Tor and proxy servers are used more than other anonymity techniques.

Enhancing data privacy and integrity in the cloud

Cloud computing is a new computing paradigm in which dynamically scalable resources are provided as a service over the Internet. One central concern in cloud computing is the privacy and integrity of data processed at the cloud. In this paper, we propose blind processing service using trusted computing mechanisms to provide improved privacy and integrity to potential users. Utilizing blind communication and execution services, a user exchanges his/her sensitive information with a cloud system via isolated processes whose execution environment and data is shielded from the rest of the system after ensuring the system has correct hardware, trusted computing base, correct credentials, and trustworthy state.