Wyniki wyszukiwania - BazTech

1

Ataki DDoS - przegląd zagrożeń i środków zaradczych

Gierszewski T., Molisz W.

Przegląd Telekomunikacyjny + Wiadomości Telekomunikacyjne

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2014

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nr 8-9

720--728

PL

Przedstawiono aktualny stan wiedzy związany z tematyką rozproszonych ataków odmowy świadczenia usług - DDoS. Tematyka jest o tyle aktualna, że współcześnie nie istnieje przyjęty, funkcjonujący sposób obrony przed atakami tego rodzaju. Jednocześnie obserwowana tendencja wzrastającej liczby ataków, a także coraz bardziej wyrafinowany ich charakter powoduje, że na rynku pojawiają się urządzenia i usługi, które mają zabezpieczać potencjalne czy potwierdzone ofiary. Podjęto próbę klasyfikacji ataków, mechanizmów obrony i wskazano motywacje atakujących.

EN

Paper presents actual state-of-the art in the field of Distributed Denial of Service Attacks - DDoS. Subject of the paper is actual, because no commonly accepted defense means exist. Since the growing trend of the volume of more and more sophisticated attacks is observed, devices and services protecting the potential victims appear on the market. Paper attempts to classify attacks, defense mechanisms and discuss motivations of attackers.

2

Usługi IP Multimedia Subsystem

Molisz W., Gałka P.

Przegląd Telekomunikacyjny + Wiadomości Telekomunikacyjne

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2011

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nr 2-3

47-52

PL

Przedstawiono usługi IP Multimedia Subsystem. Omówiono usługi tradycyjne (obecności, usługę PoC i komunikatora) oraz nowe (konferencja HD, telewizja IP na platformie IMS, scentralizowane usługi IMS oraz zunifikowana komunikacja.

EN

The article gives a brief overview of the IP Multimedia Subsystem services. The traditional IMS services are: presence, PoC and messaging, while the new ones include: HD Conference, IMS-based IPTV, ICS and the Unified Communications.

3

Wprowadzenie do architektury IP Multimedia Subsystem

Molisz W., Gałka P.

Przegląd Telekomunikacyjny + Wiadomości Telekomunikacyjne

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2009

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nr 12

2035-2038

PL

Przedstawiono zwięzły opis architektury IP Multimedia Subsystem. Omówiono rdzeń architektury, działanie i współdziałanie podstawowych elementów funkcjonalnych, interfejsów i przykład komunikacji.

EN

The article gives a brief overview of the IP Multimedia Subsystem architecture. The IMS architecture is discussed, followed by a description of basic functions and cooperation rules between them, interfaces and example of communication.

4

Ocena przeżywalności sieci bezskalowych w sytuacji celowych działań niszczących

Gierszewski T., Molisz W., Rak J.

Elektronika : konstrukcje, technologie, zastosowania

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2007

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Vol. 48, nr 9

59-64

PL

Poddano ocenie zachowanie sieci teleinformatycznych w warunkach celowych działań niszczących (ataków). Przebadano zdolność sieci o topologii bezskalowej do zapewnienia przeżywalności usług w przypadku eliminacji jej istotnych węzłów, zwanych centrami. Ukazano istotne różnice w poziomie jakości odtwarzania usług dla awarii będącej następstwem ataku w zestawieniu z przypadkiem awarii losowej. Zaproponowano również szereg topologicznych miar określających stopień przeżywalności sieci. Przeanalizowano zarówno sztuczne sieci bezskalowe, jak i sieci rzeczywiste o różnym stopniu bezskalowości. Wyniki poddano analizie porównawczej w zestawieniu z analogicznymi rezultatami uzyskanymi dla sieci o topologii regularnej.

EN

This paper evaluates the behavior of wide-area networks under malicious attacks. In particular, it investigates the capability of scale-free networks to provide service survivability under intentional removal of the most important network nodes. It shows a significant difference in the achieved level of service restoration quality between failures being the result of an attack and random failures. Several topological measures to determine the level of a network survivability have been also proposed.

5

Service restoration in survivable networks under attacks

Gierszewski T., Molisz W., Rak J.

Systems Science

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2006

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Vol. 32, no 3

15-26

EN

A comparison of service restoration quality in survivable optical transport networks OTN (WDM) degraded due to physical failures or degraded after intentional attack is described. Survivability assumptions are as follows: end-to-end path protection: preplanned node-disjoint backup path for each working path. The lightpaths optimization problem in survivable networks is NP-complete and we propose the heuristic SCNDP algorithm to solve the problem. The original author’s network simulator was used to model five network: National Science Foundation (NSF) network, PIONIER (Polish Optical Internet). Italian optical network, artificial intermediate network (AIN) and artificial scale-free network (ASF), corresponding to parameters of NSF. Single node outages being either a consequence of physical failures, or resulting from malicious attacks were simulated in each of the five networks. We showed that the differences in the effectiveness of service restoration caused by these two mechanisms are rather small in networks having regular topologies (like NSF), but in contrast, are significant in intermediate and scale-free networks (much more vulnerable to attacks). All results are the original contribution and are published for the first time.

6

End-to-end service survivability under attacks on networks

Molisz W., Rak J.

Journal of Telecommunications and Information Technology

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2006

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nr 3

19-26

EN

Network survivability is a capability of a networked system to provide its services despite failures or attacks. Attacks, e.g., due to acts of war, being potentially damaging events, were basically considered in the historical definitions of a survivability phenomenon. The meaning of the term: "network survivability" evolved in the last decade. Recently, attacks replayed the important role again. Their nature, however, including intrusions, probes, denials of service, differs from the old one. Survivability is strongly related to other fields of study. In particular, quality of service depends on network survivability. We investigate these dependencies in scale-free networks. Many networks are scale-free, i.e., their node degree distribution follows the power law. Nodes of the highest degrees, called centers, are highly vulnerable to attacks. Elimination of these nodes seriously degrades the overall performance of network services. In this paper we propose a model, which, based on traffic parameters of a demand, like delay or bit rate, allows to establish the survivable and attack proof end-to-end connections. The key idea of this model is that for the significant traffic, it establishes paths, which omit centers. The important connections become more resistant to attacks. We show that in the best case, obtained for the highest class of service, the number of broken connections is reduced even by factor 3. Example results are compared to those for the standard distance metrics. Our model is applicable to many network architectures and many classes of service.

7

Survivability issues in IP-MPLS networks

Molisz W.

Systems Science

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2005

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Vol. 31, no 4

87-107

EN

A model for survivability assessment of IP-MPLS networks implemented directly in optical transport networks OTN (WDM) is described under assumptions as follows: end-to-end path protection; preplanned node-disjoint, dedicated or shared, backup path for each working path: distributed control of all top-down restoration actions: LSP-to-lightpath mapping minimizing the number of wavelengths converters. Survivability of such networks has a fundamental importance, since a single link cut can affect extremely large traffic volumes. The optimization problem ofsurvivable routing and wavelength assignment (SRWA) can be decomposed into a survivable routing followed by a wavelength assignment optimization problem. They are stated as the mixed integer and integer programming problems, respectively. Unfortunately, they both are NP-complete. Heuristic algorithms are proposed to solve the problems. The presented approach has been verified by means of simulation. Some results of the large number of simulation experiments investigating networks: DARPA. and NSF are described and discussed. Conclusions help in better understanding of survivability issues in IP-MPLS networks. All results are the original contribution and are published for the first time.

8

Survivability issues in IP-MPLS networks

Molisz W.

Systems Science

|

2005

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Vol. 31, no 2

97-105

EN

A model for survivability assessment of IP-MPLS networks implemented directly in optical transport networks OTN (WDM) is described under assumptions as follows: end-to-end path protection; preplanned node-disjoint, dedicated or shared, backup path for each working path; distributed control of all top-down restoration actions; LSP-to-lightpath mapping minimizing the number of wavelength converters. Survivability of such networks has a fundamental importance, since a single link cut can affect extremely large traffic volumes. The optimization problem of survivable routing and wavelength assignment (SRWA) can be decomposed into a survivable routing followed by a wavelength assignment optimization problem. They are stated as the mixed integer and integer programming problems, respectively. Unfortunately, they both are NP-complete. Heuristic algorithms are proposed to solve the problems. The presented approach has been verified by means of simulation. Some results of the large number of simulation experiments investigating networks: DARPA, and NSF are described and discussed. Conclusions help in better understanding of survivability issues in IP-MPLS networks. All results are the original contribution and are published for the first time.

9

Model przeżywalnych sieci IP następnej generacji

Molisz W.

Zeszyty Naukowe Wydziału ETI Politechniki Gdańskiej. Technologie Informacyjne

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2004

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nr 4

511--518

PL

W pracy rozważa się przeżywalne sieci o warstwowej architekturze logicznej IP-MPLS/ WDM. Węzły analizowanej sieci mają zintegrowaną funkcjonalność ruterów IP-MPLS w warstwie IP oraz przełącznic optycznych (OXC) w warstwie transmisji optycznej. Przepustowości łączy mogą być tak duże (nawet kilkaset Gbit/s), że awaria nawet pojedynczego łącza może dotknąć bardzo liczne grupy użytkowników. Dlatego zasadnicze znaczenie ma zapewnienie przeżywalności tych sieci. W pracy rozważa się zadania optymalizacji strumieni informacji (IP), jakie sieć ma przesłać w warstwie optycznej między zadanymi parami użytkowników przy możliwie najmniejszym koszcie, spełnieniu wszystkich standardowych ograniczeń w taki sposób, aby uszkodzenie pojedynczego węzła lub światłowodu nie przeszkodziło w transmisji. Przedstawiono model umożliwiający badanie przeżywalnych sieci IP oraz przykładowe wyniki symulacji i wnioski.

EN

This paper deals with survivable networks having layered architecture IP-MPLSIWDM. Nodes have integrated functionality of IP-MPLS routers in the IP layer and of optical cross connects in the optical transmission layer. Since link capacities may approach several hundreds of gigabits per second, even a single link failure may affect very large groups of users. Network survivability becomes really the fundamental issue. The IP flow optimization problem, satisfying given demands at minimum cost and protecting flows in the optical layer against a single are (o(- a single node) failure, is considered. Methods solving the problem and simulation results are described.

10

Wprowadzenie do architektury sieci Ethernet 10 Gbit/s

Molisz W., Tołwiński T.

Przegląd Telekomunikacyjny + Wiadomości Telekomunikacyjne

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2004

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nr 2-3

64-68

PL

Przedstawiono zwięzły opis architektury sieci Ethernet 10 Gbit/s. Omówiono ewolucję architektury logicznej sieci Ethernet, działanie i współdziałanie podstawowych podwarstw, interfejsów i elementów funkcjonalnych.

EN

The article gives a brief overview of the logical architecture of Ethernet 10 Gbps. The evolution of logical architecture of Ethernet from 10 Mbps to 10 Gbps is discussed, followed by a description of functions and cooperation rules between basic sublayers, interfaces and functional components.

11

Self-healing ATM networks based on preplanned restoration of virtual paths.

Molisz W.

Systems Science

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2002

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Vol. 28, nr 2

107-30

EN

Network survivability is critical for service continuity in the information era. This article focuses on restoration strategies in self-healing ATM networks, based on virtual paths (VPs). The article briefly categorizes restoration techniques in SONET/SDH networks, as well as in ATM networks, and compares them. Then a particular self-healing scheme, operating on preplanned backup VPs, suitable for mesh-type networks is described in detail. Based on this scheme, the simulation programs have been implemented, and verified. The method is illustrated by simulation experiments of the typical wide area ATM network in Poland.