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Copyright of Information Technology & Control is the property of Kaunas University of Technology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

In this paper we evaluate a commonly used testing tool of Internet applications and services – PlanetLab. PlanetLab is a large-scale network of Linux servers used for Internet development and research. The geographical diversity of the servers allows engineers and researchers to test networking applications in the real Internet worldwide. In the paper we evaluate PlanetLab from different points of view we identified based on its long-term use. We specifically deal with the problematic aspects, such as PlanetLab service availability, networking performance, geographical accuracy, and DNS addressing correctness. Some of the PlanetLab ‘negative’ properties evaluated in this paper are required and needed as PlanetLab was established to reflect the real (erroneous) communication in the Internet. Nevertheless, one should be aware of them to set-up experiments correctly, run them smoothly, and not to misinterpret the results. Based on the observations presented, we give a set of simple conclusions that should help engineers to achieve valid Internet experiment results. [ABSTRACT FROM AUTHOR]

Copyright of Information Technology & Control is the property of Kaunas University of Technology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

COVID-19 has disrupted every field of life and education is not immune to it. Student learning and examinations moved on-line on a few weeks notice, which has created a large workload for academics to grade the assessments and manually detect students' dishonesty. In this paper, we propose a method to automatically indicate cheating in unproctored on-line exams, when somebody else other than the legitimate student takes the exam. The method is based on the analysis of the student's on-line traces, which are logged by distance education systems. We work with customized IP geolocation and other data to derive the student's cheating risk score. We apply the method to approx. 3600 students in 22 courses, where the partial or final on-line exams were unproctored. The found cheating risk scores are presented along with examples of indicated cheatings. The method can be used to select students for knowledge re-validation, or to compare student cheating across courses, age groups, countries, and universities. We compared student cheating risk scores between four academic terms, including two terms of university closure due to COVID-19. [ABSTRACT FROM AUTHOR]

The paper deals with the locations of IP addresses that were used in the past. This retrospective geolocation suffers from continuous changes in the Internet space and a limited availability of past IP location databases. I analyse the retrospective geolocation of IPv4 and IPv6 addresses over five years. An approach is also introduced to handle missing past IP geolocation databases. The results show that it is safe to retrospectively locate IP addresses by a couple of years, but there are differences between IPv4 and IPv6. The described parametric model of location lifetime allows us to estimate the time when the address location changed in the past. The retrospective geolocation of IP addresses has a broad range of applications, including social studies, system analyses, and security investigations. Two longitudinal use cases with the applied results are discussed. The first deals with geotargeted online content. The second deals with identity theft prevention in e-commerce. [ABSTRACT FROM AUTHOR]