667 research outputs found

    Traffic measurement and analysis

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    Measurement and analysis of real traffic is important to gain knowledge about the characteristics of the traffic. Without measurement, it is impossible to build realistic traffic models. It is recent that data traffic was found to have self-similar properties. In this thesis work traffic captured on the network at SICS and on the Supernet, is shown to have this fractal-like behaviour. The traffic is also examined with respect to which protocols and packet sizes are present and in what proportions. In the SICS trace most packets are small, TCP is shown to be the predominant transport protocol and NNTP the most common application. In contrast to this, large UDP packets sent between not well-known ports dominates the Supernet traffic. Finally, characteristics of the client side of the WWW traffic are examined more closely. In order to extract useful information from the packet trace, web browsers use of TCP and HTTP is investigated including new features in HTTP/1.1 such as persistent connections and pipelining. Empirical probability distributions are derived describing session lengths, time between user clicks and the amount of data transferred due to a single user click. These probability distributions make up a simple model of WWW-sessions

    The SPAN cookbook: A practical guide to accessing SPAN

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    This is a manual for remote users who wish to send electronic mail messages from the Space Physics Analysis Network (SPAN) to scientific colleagues on other computer networks and vice versa. In several instances more than one gateway has been included for the same network. Users are provided with an introduction to each network listed with helpful details about accessing the system and mail syntax examples. Also included is information on file transfers, remote logins, and help telephone numbers

    Grid computing for the numerical reconstruction of digital holograms

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    Digital holography has the potential to greatly extend holography's applications and move it from the lab into the field: a single CCD or other solid-state sensor can capture any number of holograms while numerical reconstruction within a computer eliminates the need for chemical processing and readily allows further processing and visualisation of the holographic image. The steady increase in sensor pixel count and resolution leads to the possibilities of larger sample volumes and of higher spatial resolution sampling, enabling the practical use of digital off-axis holography. However this increase in pixel count also drives a corresponding expansion of the computational effort needed to numerically reconstruct such holograms to an extent where the reconstruction process for a single depth slice takes significantly longer than the capture process for each single hologram. Grid computing - a recent innovation in largescale distributed processing -provides a convenient means of harnessing significant computing resources in an ad-hoc fashion that might match the field deployment of a holographic instrument. In this paper we consider the computational needs of digital holography and discuss the deployment of numericals reconstruction software over an existing Grid testbed. The analysis of marine organisms is used as an exemplar for work flow and job execution of in-line digital holography

    Handbook of solar-terrestrial data systems, version 1

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    The interaction between the solar wind and the earth's magnetic field creates a large magnetic cavity which is termed the magnetosphere. Energy derived from the solar wind is ultimately dissipated by particle acceleration-precipitation and Joule heating in the magnetosphere-ionosphere. The rate of energy dissipation is highly variable, with peak levels during geomagnetic storms and substorms. The degree to which solar wind and magnetospheric conditions control the energy dissipation processes remains one of the major outstanding questions in magnetospheric physics. A conference on Solar Wind-Magnetospheric Coupling was convened to discuss these issues and this handbook is the result

    ECHO Facts for Users 1/97

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    ECHO = European Community Humanitarian Offic

    CERN UNIX user guide

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    Determining the effectiveness of deceptive honeynets

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    Over the last few years, incidents of network based intrusions have rapidly increased, due to the increase and popularity of various attack tools easily available for download from the Internet. Due to this increase in intrusions, the concept of a network defence known as Honeypots developed. These honeypots are designed to ensnare attackers and monitor their activities. Honeypots use the principles of deception such as masking, mimicry, decoying, inventing, repackaging and dazzling to deceive attackers. Deception exists in various forms. It is a tactic to survive and defeat the motives of attackers. Due to its presence in the nature, deception has been widely used during wars and now in Information Systems. This thesis considers the current state of honeypot technology as well as describes the framework of how to improve the effectiveness of honeypots through the effective use of deception. In this research, a legitimate corporate deceptive network is created using Honeyd (a type of honeypot) which is attacked and improved using empirical learning approach. The data collected during the attacking exercise were analysed, using various measures, to determine the effectiveness of the deception in the honeypot network created using honeyd. The results indicate that the attackers were deceived into believing the honeynet was a real network which instead was a deceptive network

    Cashing in on ATM Malware. A Comprehensive Look at Various Attack Types

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    ATM malware is one of the digital threats that have been around for a while now, with the discovery of the first known variant dating back to 2009. It should not be a surprise that it has become a mainstay in many cybercriminals’ arsenal because it can, plainly put, steal cold, hard cash. Trend Micro Forward-Looking Threat Research (FTR) Team and Europol’s European Cybercrime Centre (EC3
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