Article
Технология анонимных сетей
We propose a new method of optimal route search for an overlay channel built on top of a wireless sensor network. It allows to increase utilization of unused telecommunication and energy resources in wireless sensor networks without loss of their primary functions.
Huge computer networks composed of infected machines so called botnets are currently the one of the most dangerous threats for global society. Botnets are a brilliant tool for organizing distributed denial of service attacks, sending spam and phishing email, stealing sensitive information and money from various accounts. Hackers create botnets from any kind of electronic devices connected to the Internet. The most widely used devices are: personal computers with windows operating system, smartphones with Android OS, IoT devices with public IP addresses and open vulnerabilities (IPTV cameras, for example). There are a lot of options for botnet hiring on the darknet. It is possible to hire a botnet, buy a builder kit or any other service in hacker-to-hacker manner. The easiest way to build a botnet is a creation of central server for spreading commands and creation of clients (bots) that will connect to this server. Such botnets are so called traditional botnets. Traditional botnets with centralized command and control mechanism are vulnerable to the wide range of attacks. For example, if one particular bot is captured by the security analyst the IP address of command and control server will be compromised with very high probability. Without central command and control server botnet is useless because the malefactor is unable to spread commands over infected network. In order to make botnets more robust and steady the peer-to-peer botnet architecture was introduced. P2P architectures could be divided on 3 main categories: pure, moderated and hybrid. The aim of the current papers is covering peer to peer botnets and its architecture.
This work studies the possibility of using a widely adopted peer-to-peer (P2P) data transmission protocol named BitTorrent for the purpose of building a data storage and distribution system that would allow numerous institutions to access vast unstructured volumes of scientic data. We discuss the practical efficiency of using this technology depending on the typical file sizes and readily available software, the ratio of read and write operations, computational power available at the tracker server, the number of mirrors and simultaneously connected clients.
A model for organizing cargo transportation between two node stations connected by a railway line which contains a certain number of intermediate stations is considered. The movement of cargo is in one direction. Such a situation may occur, for example, if one of the node stations is located in a region which produce raw material for manufacturing industry located in another region, and there is another node station. The organization of freight traffic is performed by means of a number of technologies. These technologies determine the rules for taking on cargo at the initial node station, the rules of interaction between neighboring stations, as well as the rule of distribution of cargo to the final node stations. The process of cargo transportation is followed by the set rule of control. For such a model, one must determine possible modes of cargo transportation and describe their properties. This model is described by a finite-dimensional system of differential equations with nonlocal linear restrictions. The class of the solution satisfying nonlocal linear restrictions is extremely narrow. It results in the need for the “correct” extension of solutions of a system of differential equations to a class of quasi-solutions having the distinctive feature of gaps in a countable number of points. It was possible numerically using the Runge–Kutta method of the fourth order to build these quasi-solutions and determine their rate of growth. Let us note that in the technical plan the main complexity consisted in obtaining quasi-solutions satisfying the nonlocal linear restrictions. Furthermore, we investigated the dependence of quasi-solutions and, in particular, sizes of gaps (jumps) of solutions on a number of parameters of the model characterizing a rule of control, technologies for transportation of cargo and intensity of giving of cargo on a node station.
Event logs collected by modern information and technical systems usually contain enough data for automated process models discovery. A variety of algorithms was developed for process models discovery, conformance checking, log to model alignment, comparison of process models, etc., nevertheless a quick analysis of ad-hoc selected parts of a journal still have not get a full-fledged implementation. This paper describes an ROLAP-based method of multidimensional event logs storage for process mining. The result of the analysis of the journal is visualized as directed graph representing the union of all possible event sequences, ranked by their occurrence probability. Our implementation allows the analyst to discover process models for sublogs defined by ad-hoc selection of criteria and value of occurrence probability
The geographic information system (GIS) is based on the first and only Russian Imperial Census of 1897 and the First All-Union Census of the Soviet Union of 1926. The GIS features vector data (shapefiles) of allprovinces of the two states. For the 1897 census, there is information about linguistic, religious, and social estate groups. The part based on the 1926 census features nationality. Both shapefiles include information on gender, rural and urban population. The GIS allows for producing any necessary maps for individual studies of the period which require the administrative boundaries and demographic information.
It is well-known that the class of sets that can be computed by polynomial size circuits is equal to the class of sets that are polynomial time reducible to a sparse set. It is widely believed, but unfortunately up to now unproven, that there are sets in EXPNP, or even in EXP that are not computable by polynomial size circuits and hence are not reducible to a sparse set. In this paper we study this question in a more restricted setting: what is the computational complexity of sparse sets that are selfreducible? It follows from earlier work of Lozano and Torán (in: Mathematical systems theory, 1991) that EXPNP does not have sparse selfreducible hard sets. We define a natural version of selfreduction, tree-selfreducibility, and show that NEXP does not have sparse tree-selfreducible hard sets. We also construct an oracle relative to which all of EXP is reducible to a sparse tree-selfreducible set. These lower bounds are corollaries of more general results about the computational complexity of sparse sets that are selfreducible, and can be interpreted as super-polynomial circuit lower bounds for NEXP.