TSE-IDS: A Two-Stage Classifier Ensemble for Intelligent Anomaly-based Intrusion Detection System

Intrusion detection systems (IDS) play a pivotal role in computer security by discovering and repealing malicious activities in computer networks. Anomaly-based IDS, in particular, rely on classification models trained using historical data to discover such malicious activities. In this paper, an improved IDS based on hybrid feature selection and two-level classifier ensembles is proposed. An hybrid feature selection technique comprising three methods, i.e. particle swarm optimization, ant colony algorithm, and genetic algorithm, is utilized to reduce the feature size of the training datasets (NSL-KDD and UNSW-NB15 are considered in this paper). Features are selected based on the classification performance of a reduced error pruning tree (REPT) classifier. Then, a two-level classifier ensembles based on two meta learners, i.e., rotation forest and bagging, is proposed. On the NSL-KDD dataset, the proposed classifier shows 85.8% accuracy, 86.8% sensitivity, and 88.0% detection rate, which remarkably outperform other classification techniques recently proposed in the literature. Results regarding the UNSW-NB15 dataset also improve the ones achieved by several state of the art techniques. Finally, to verify the results, a two-step statistical significance test is conducted. This is not usually considered by IDS research thus far and, therefore, adds value to the experimental results achieved by the proposed classifier

Mediterranean trade in the Pyrenees: Italian merchants in Puigcerdà, 1300-1360.

A partir de les evidències notarials que encara existeixen de la pirinenca vila de Puigcerdà, aquest article investiga la connexió entre l’interior de les regions muntanyoses de la Mediterrània i les xarxes comercials mediterrànies més extenses a la fi de l’Edat Mitjana. Es mostra que, seguint la ràpida expansió de la producció de draps als Pirineus catalans durant el final del segle xiii, mercaders italians (la majoria toscans), alguns dels quals provinents de petites ciutats d’in- terior, van començar a viatjar no només des dels principals ports de la Mediterrània, sinó cap a l’interior del Pirineu català, on venien draps tenyits des de finals de l’any 1302. Sembla que l’activitat comercial d’aquests mercaders es va incrementar durant les primeres dècades del segle xiv, ja que la producció de draps a Puigcerdà va continuar creixent i va persistir fins a finals de la dècada dels anys seixanta del mateix segle. Aquest article, mitjançant una comparació entre el nombre de mercaders italians actius a Puigcerdà i a la petita vila catala- na de Castelló d’Empúries, revela que el nivell d’accés dels productors mediterranis en el comerç a l’interior de les regions muntanyoses va ser significativament més baix que el de la costa. Sembla també que les dues viles formen part d’una xarxa interconnectada que va veure alguns dels mateixos mercaders comerciants a Puigcerdà i a Castelló. Probablement, aquesta xarxa tenia la base a Perpinyà, amb un alt nombre d’italians mercaders com a residents. El nombre d’italians venedors de tint a la costanera Castelló va superar de llarg els de Puigcerdà, la qual cosa suggereix que, si bé els Pirineus interiors estaven vinculats al comerç mediterrani, aquestes connexions econòmiques eren menys denses que les de les zones costaneres i més limitades per la geografia local.Based on an examination of surviving notarial evidence from the Pyrenean town of Puigcerdà, this article investigates the ties between the inland mountainous regions of the Mediterranean and broader Mediterranean trade net- works in the later Middle Ages. It shows that, following the rapid expansion of cloth production in the Catalan Pyrenees during the late thirteenth century, Italian (mainly Tuscan) merchants, some themselves from smaller interior towns, began travelling not only to the major Mediterranean coastal ports but also, through them, into the inner Catalan Pyrenees, where they sold cloth-dyeing materials from at least 1302 on. The commercial activity of these merchants appears to have grown during the first decades of the fourteenth century as cloth production in Puigcerdà continued to grow and persisted at least into the 1360s. Through a comparison between the number of Italian merchants operating in Puigcerdà and those in the smaller Catalan town of Castelló d’Empúries, this article also reveals that the level of access to Mediterranean products and trade in inland mountainous regions was significantly lower than that of the coast. Both towns appear to have been part of one interconnected network that saw some of the same merchants trading in Puigcerdà and in Castelló. This network was likely based in Perpignan, where a high number of the Italian merchants resided. The number of Italian dyesellers in coastal Castelló far outstripped those in Puigcerdà, suggesting that while the inner Pyrenees were tied to Mediterranean trade, these economic connections were less dense than those in coastal areas, and more limited by local geography.A partir de las evidencias notariales que se han conservado en la pirenaica villa de Puigcerdà, este artículo investiga la conexión entre el interior de las regiones montañosas del Mediterráneo y las redes comerciales mediterráneas más amplias a finales de la Edad Media. Se muestra que, siguiendo la rápida expansión de la producción de paños en los Pirineos Catalanes durante el final del siglo XIII, mercaderes italianos (la mayoría toscanos), algunos de ellos provenientes de pequeñas ciudades de interior, comenzaron a viajar no solo desde los principales puertos del Mediterráneo, sino hacia el interior del Pirineo catalán, donde vendían paños teñidos desde finales de 1302. La actividad comercial de estos mercaderes parece que se incrementó durante las primeras décadas del siglo XIV, ya que la producción de paños en Puigcerdà continuó creciendo y persistió hasta finales de la década de los sesenta del mismo siglo. Este artículo, mediante una comparación entre el número de mercaderes italianos activos en Puigcerdà y en la pequeña villa catalana de Castelló d’Empúries, revela que el nivel de acceso de los productores mediterráneos al comercio en el interior de las regiones montañosas fue significativamente más bajo que el de la costa. Ambas villas parece que forman parte de una red interconectada que vio algunos de los mismos mercaderes comerciantes en Puigcerdà y en Castelló. Esta red probablemente estaba basada en Perpiñán, con un alto número de mercaderes italianos residentes. El número de italianos vendedores de tinte en la costera Castelló superaron por mucho a los de Puigcerdà, lo que sugiere que, si bien los Pirineos interiores estaban vinculados al comercio mediterráneo, estas conexiones económicas eran menos densas que las de las zonas costeras y más limitadas por la geografía local.

Sistemi di controllo manageriale e strategia aziendale. Analisi delle medie imprese del nordest

Il presente lavoro si inserisce nell\u2019ambito della copiosa letteratura che, a partire dagli anni Ottanta, ha affrontato il tema della progettazione e dell\u2019uso dei sistemi di controllo manageriale secondo l\u2019approccio contingente (Otley, 2016). L\u2019impostazione di riferimento \ue8 la teoria organizzativa della contingenza, che, applicata al tema del controllo aziendale, postula l\u2019assunto secondo il quale la scelta ottima in termini di architettura dei sistemi di controllo dipende dalla specifica configurazione assunta da alcune variabili interne ed esterne: struttura organizzativa, dimensione aziendale, complessit\ue0 ambientale, tecnologia, cultura, strategia (Chenhall, 2003). Coerentemente con l\u2019impostazione contingente, gli sforzi della ricerca scientifica si sono indirizzati verso lo studio del come i sistemi di controllo dovrebbero essere progettati e utilizzati per adattarsi ai contesti specifici di applicazione, tenendo conto dell\u2019evolversi di questi ultimi. Nel tentativo di offrire un contributo al dibattito in corso, il presente lavoro si pone l\u2019obiettivo di ricercare se esista una reciproca influenza tra l\u2019architettura dei sistemi di controllo e le scelte strategiche di business in uso nelle medie imprese del nordest e quali siano le eventuali ripercussioni sia in termini di controllo, sia di strategia. Per perseguire la summenzionata finalit\ue0, sul piano concettuale si \ue8 scelto di utilizzare il modello LOC (Levers Of Control) di Simons (1995) per la variabile \u201ccontrollo\u201d e i tipi strategici di Miles and Snow (1978) per la variabile \u201cstrategia\u201d. Sul piano metodologico, si \ue8 scelto di svolgere la raccolta di dati su ampia scala mediante l\u2019invio di un questionario strutturato all\u2019intera popolazione delle 1.249 medie imprese del nordest. I dati acquisiti, corrispondenti ad un tasso di risposta del 18%, sono stati analizzati con tecniche quantitative di analisi statistica. L\u2019analisi dei dati evidenzia un utilizzo di tutte le leve del controllo, con prevalenza della leva diagnostica, e una flessibilit\ue0 di comportamento sul piano strategico che di fatto impedisce di riconoscere in modo puntuale i cluster strategici del modello di Miles and Snow. Sul piano del controllo, la pratica aziendale sembra confermare l\u2019esistenza di una tensione dinamica tra le differenti leve del controllo e l\u2019uso del controllo come sistema integrato (Malmi, Brown, 2008; Tuomela, 2005). Tali scelte sembrano coerenti con la mancanza di un unico, stabile orientamento strategico aziendale e supportano comportamenti indirizzati a sostenere contemporaneamente differenti pattern strategici, a seconda delle opportunit\ue0 che il management giudica interessanti da perseguire

Describing and Verifying Monitoring Capabilities for Service Based Systems

Monitoring the operation of Service Based Systems (SBS) to ensure compliance with a set of service level agreements (SLAs) for example cannot always rely on a pre-specified monitoring infrastructure, where all the information and components required for monitoring are a priori known and available. This because new services with unknown monitoring infrastructures and capabilities may be dynamically assembled to an SBS. To address the need for dynamic configuration of SBS monitoring infrastructures, this paper proposes a model for describing the monitoring capabilities of different services of an SBS and discusses the process for verifying the monitorability of required properties based on these capabilities

Dynamic set-up of monitoring infrastructures for service based systems

Service based systems are intrinsically dynamic as the services deployed by them can be replaced at runtime. When this happens, the Service Level Agreements (SLAs) that regulate the provision of services may also need to change. Following such changes, the monitoring infrastructure that is used to monitor SLAs may also need to be modified to ensure the continuous provision of the necessary runtime checks. This paper presents a framework that supports the dynamic assessment of the monitorability of SLAs terms and the dynamic setup of an appropriate infrastructure for monitoring them following such changes. The monitorability checks are based on comparisons between the SLA terms for specific services and descriptions of the monitoring capabilities of these services which are expressed in languages introduced in the paper. The paper presents a prototype implementation of the framework and the results of a preliminary evaluation of it

A utility-based model to define the optimal data quality level in IT service offerings

In the information age, enterprises base or enrich their core business activities with the provision of informative services. For this reason, organizations are becoming increasingly aware of data quality issues, which concern the evaluation of the ability of a data collection to meet users’ needs. Data quality is a multidimensional and subjective issue, since it is defined by a variety of criteria, whose definition and evaluation is strictly dependent on the context and users involved. Thus, when considering data quality, the users’ perspective should always be considered fundamental. Authors in data quality literature agree that providers should adapt, and consequently improve, their service offerings in order to completely satisfy users’ demands. However, we argue that, in service provisioning, providers are subject to restrictions stemming, for instance, from costs and benefits assessments. Therefore, we identify the need for a conciliation of providers’ and users’ quality targets in defining the optimal data quality level of an informative service. The definition of such equilibrium is a complex issue since each type of user accessing the service may define different utilities regarding the provided information. Considering this scenario, the paper presents a utility-based model of the providers’ and customers’ interests developed on the basis of multi-class offerings. The model is exploited to analyze the optimal service offerings that allow the efficient allocation of quality improvements activities for the provider

A Framework for Hierarchical and Recursive Monitoring of Service Based Systems

Runtime monitoring of Service Based Systems (SBSs) usually relies on information derived from I/O messages exchanged within business processes implementing services. When service provisioning is regulated by complex Service Level Agreements (SLAs) between service requesters, (composed) services, and infrastructure providers, monitoring may require additional features, such as (i) coordination among events captured at different sources involved in service provisioning and (ii) delegation of properties monitoring to local sites. This paper discusses an architecture and engagement protocol supporting the two aforementioned requirements for monitoring complex SLA-driven service provisioning

Online anomaly detection using statistical leverage for streaming business process events

While several techniques for detecting trace-level anomalies in event logs in offline settings have appeared recently in the literature, such techniques are currently lacking for online settings. Event log anomaly detection in online settings can be crucial for discovering anomalies in process execution as soon as they occur and, consequently, allowing to promptly take early corrective actions. This paper describes a novel approach to event log anomaly detection on event streams that uses statistical leverage. Leverage has been used extensively in statistics to develop measures to identify outliers and it has been adapted in this paper to the specific scenario of event stream data. The proposed approach has been evaluated on both artificial and real event streams.Comment: 12 pages, 4 figures, conference (Proceedings of the 1st International Workshop on Streaming Analytics for Process Mining (SA4PM 2020) in conjunction with International Conference on Process Mining, Accepted for publication (Sep 2020)