Linux System Research Articles

리눅스 서버의 사용자 관리 및 보안

개방형 운영체제인 리눅스는 전통적인 웹, 메일, DNS, FTP 등의 서버뿐만 아니라, 클라우드 및 빅데이터 인프라 구축에도 사용되고 있다. 또한 데스크톱이나 모바일 기기, 스마트 TV 및 자동차 등에도 탑재되고 있다. 특히, 사물인터넷 시대로 접어드는 현 시점에서는 리눅스가 차지하는 비중이 더 커질 것으로 예상되고 있다. 리눅스의 사용이 증가함에 따라 보안이 중요한 요소로 부각되고 있고, 리눅스 시스템 보안의 핵심은 사용자 관리에 있다. 본 논문에서는 리눅스의 사용자를 분류하고, 사용자 관련 파일의 역할을 분석하였다. 마지막으로 리눅스의 사용자별 보안 관리 기법에 대해 알아보고, 유용한 사용자 보안 도구에 대해 분석하였다. Open operating system, Linux is the traditional Web, E-mail, DNS, FTP server, as well as being used in Cloud and Big data infrastructure. In addition, Linux is also used like a desktop or mobile devices, smart TV and cars. In particular, stepping up to the IoT era at this time is expected to be greater proportion occupied by Linux. As the use of Linux has increased security has emerged as an important factor. User management is core of Linux system security. In this paper, Classifying Linux user and analyzed the role of the user-specific file. Finally, we analyzed the linux management technologies and useful user security tools.

Linux 기반에서 빠른 프로그램 실행을 위한 주소 공간 유지 기법

The environment of Internet of Things (IoT) wherein various devices are connected through the Internet with value-added network functions, is currently a subject of active study. Accordingly, the existing computing environment based on desktop or mobile systems is being expanded into a computing environment of more diverse devices. Because the response of program launching is important in terms of User Experience (UX) in IoT environments, the technology for guaranteeing rapid response of program launching in IoT devices is getting the focus of much current research. In this paper we analyze the Zygote technique, which is being used for faster program execution in Android systems, and, based on our results, we propose an address space maintaining scheme for the rapid launching of programs for use in Linux-based systems. Our scheme utilizes the Copy on Write (CoW) technique in Linux systems as well as the Zygote technique of Android systems. In order to evaluate the proposed scheme, we implemented our scheme on Linux systems and performed several experiments. The experimental results show that the proposed scheme shortens the launching time up to 99%, compared to the existing technique.

LTE 기반 모바일 DaaS 환경에서 비디오 스트리밍을 위한 Linux TCP 구현물의 실험적 성능 분석

Recent network environment has been rapidly evolved to cloud computing environment based on the development of the Internet technologies. Furthermore there is an increasing demand on mobile cloud computing due to explosive growth of smart devices and wide deployment of LTE-based cellular networks. Thus mobile Desktop-as-a-Service(DaaS) could be a pervasive service for nomadic users. In addition, video streaming traffic is currently more than two-thirds of mobile traffic and ever increasing. All such trends enable that video streaming in mobile DaaS could be an important concern for mobile cloud computing. It should be noted that the performance of the Transmission Control Protocol(TCP) on cloud host servers greatly affects Quality of Service(QoS) of video streams for mobile users. With widely deployed Linux server platforms for cloud computing, in this paper, we conduct an experimental analysis of the twelve Linux TCP variants in mobile DaaS environments. The results of our experiments show that the TCP Illinois outperforms the other TCP variants in terms of wide range of packet loss rate and propagation delay over LTE-based wireless links between cloud servers and mobile devices, even though TCP CUBIC is usually used in default in the current Linux systems.

Fast Fourier transform benchmark on X86 Xeon system for multimedia data processing

I benchmarking the well-known Fast Fourier Transforms Library at X86 Xeon E5 2690 v3 system. Fourier transform image processing is an important tool that is used to decompose the image into sine and cosine components. If the input image represented by the equation in the spatial domain, output from the Fourier transform represents the image in the fourier or the frequency domain. Each point represents a particular frequency included in the spatial domain image in the Fourier domain image. Fourier transform is used widely for image analysis, image filtering, image compression and image reconstruction as a wide variety of applications. Fourier transform plays a important role in signal processing, image processing and speech recognition. It has been used in a wide range of sectors. For example, this is often a signal processing, is used in digital signal processing applications, such as voice recognition, image processing. The Discrete Fourier transform is a specific kind of Fourier transform. It maps the sequence over time to sequence over frequencies. If it implemented as a discrete Fourier transform, the time complexity is O (N2). It's actually not a better way to use. Alternatively, the Fast Fourier Transform is possible to easily perform a Discrete Fourier Transform of parallelism with only O (n log n) algorithm. Fast Fourier Transform is widely used in a variety of scientific computing program. If you are using the correct library can improve the performance of the program, without any additional effort. I have a well-known fast Fourier transform library was going to perform a benchmarking on X86 based Intel Xeon E5 2690 systems. In the machine's current Intel Xeon X86 Linux system. I have installed Intel IPP library, FFTW3 Library (West FFT), Kiss -FFT library and the numutils library on Intel X86 Xeon E5 based systems. The benchmark performed at C, and measuring the performance over a range of a transform size. It benchmarks both real and complex transforms in one dimension.

Linux Low-Latency Tracing for Multicore Hard Real-Time Systems

Real-time systems have always been difficult to monitor and debug because of the timing constraints which rule out any tool significantly impacting the system latency and performance. Tracing is often the most reliable tool available for studying real-time systems. The real-time behavior of Linux systems has improved recently and it is possible to have latencies in the low microsecond range. Therefore, tracers must ensure that their overhead is within that range and predictable and scales well to multiple cores. The LTTng 2.0 tools have been optimized for multicore performance, scalability, and flexibility. We used and extended the real-time verification tool rteval to study the impact of LTTng on the maximum latency on hard real-time applications. We introduced a new real-time analysis tool to establish the baseline of real-time system performance and then to measure the impact added by tracing the kernel and userspace (UST) with LTTng. We then identified latency problems and accordingly modified LTTng-UST and the procedure to isolate the shielded real-time cores from the RCU interprocess synchronization routines. This work resulted in extended tools to measure the real-time properties of multicore Linux systems, a characterization of the impact of LTTng kernel and UST tracing tools, and improvements to LTTng.

Parity Resynchronization using a Block-level Journaling for Software RAID

Software redundant arrays of independent disks (RAID) suffer from several hours of resynchronization time after a sudden power-off. Data blocks and a parity block in a stripe must be updated in a consistent manner. However, a data block may be updated without a parity update if power goes off. Such a partially modified stripe must be updated with a correct parity block after a reboot. It is difficult, however, to find which stripe is partially updated. The widely used traditional parity resynchronization approach entails a very long process that scans the entire volume to find and fix partially updated stripes. As a remedy to this problem, this paper presents a parity resynchronization scheme that exhibits a small overhead for a wide range of workloads, finishes parity resynchronization within several minutes, and is transparent to file systems, thanks to a new seamless block-level journaling. The proposed scheme is integrated into a software RAID driver in a Linux system. A performance evaluation demonstrates that the proposed scheme shortens the resynchronization process from 200min to 30s with 1% overhead, compared to 51% overhead for the prior scheme.

듀얼 버스 시스템에서의 공유 메모리 커널 모듈 구현

본 논문에서는 프로세서별 서로 다른 버스에 서로 다른 운영체제를 갖는 멀티코어 시스템에서 공유 메모리 기능을 구현하고, 임베디드 리눅스 시스템을 통하여 두 프로세서 사이에서 공유 메모리 기능을 실험하였다. 듀얼 버스 구조에서 공유 메모리 구현을 위해 메모리 컨트롤러를 이용하였으며, 리스트 자료구조를 통하여 공유 메모리 세그먼트를 관리한다. AMP 멀티 코어 실험을 위하여 2개의 프로세서 코어에 리눅스 운영체제를 탑재하도록 하였다. 그리고 공유 메모리 테스트를 위하여 구현된 커널 모듈을 이용하여 공유 메모리 생성 및 이용이 가능함을 확인 하였다. In this paper, shared memory feature was developed in multi-core system with different OS for different processor-specific bus, while conducting an experiment on shared memory feature between the two processors based on embedded Linux system. For the purpose of developing shared memory in dual bus structure, memory controller was used, while managing shared memory segment through list data structure. For AMP multi-core test, Linux OS was installed in 2 processor cores. In addition, it verified the creation and use of shared memory by using kernel module implemented to test shared memory.

PDIviz: analysis and visualization of protein-DNA binding interfaces.

Summary: Specific recognition of DNA by proteins is a crucial step of many biological processes. PDIviz is a plugin for the PyMOL molecular visualization system that analyzes protein–DNA binding interfaces by comparing the solvent accessible surface area of the complex against the free protein and free DNA. The plugin provides three distinct three-dimensional visualization modes to highlight interactions with DNA bases and backbone, major and minor groove, and with atoms of different pharmacophoric type (hydrogen bond donors/acceptors, hydrophobic and thymine methyl). Each mode comes in three styles to focus the visual analysis on the protein or DNA side of the interface, or on the nucleotide sequence. PDIviz allows for the generation of publication quality images, all calculated data can be written to disk, and a command line interface is provided for automating tasks. The plugin may be helpful for the detailed identification of regions involved in DNA base and shape readout, and can be particularly useful in rapidly pinpointing the overall mode of interaction.Availability and implementation: Freely available at http://melolab.org/pdiviz/ as a PyMOL plugin. Tested with incentive, educational, and open source versions of PyMOL on Windows, Mac and Linux systems.Contact: aschueller@bio.puc.clSupplementary Information: Supplementary data are available at Bioinformatics online.

Energy‐efficient CPU frequency control for the Linux system

SummaryEfficiency of energy usage in computing systems improves, however, still not at the rate matching the climbing demand for computing capacity. To address this urging problem, computing elements of the latest generation, that is, CPUs/graphics processing units, memory units, and network interface cards, have been designed to operate in multiple modes with differentiated energy consumption levels. Mode switching and high‐frequency performance monitoring functions have also been exposed by co‐designed abstract programming interfaces. The challenge of energy‐efficient computing is to develop hardware control mechanisms taking advantage of the new capabilities. This paper aims at giving an insight into the structure of optimal energy‐aware CPU frequency scaling rules. It gives a characterization of solutions to the optimal control problem of energy‐efficient real‐time packet inspection performed by a Linux server. A class of CPU frequency switching rules, exploiting dynamic voltage and frequency scaling mechanisms, is constructed based on experimentally identified model of server operations. The control rules are demonstrated to outperform the default CPU frequency scaling governor for the Linux kernel, both in terms of achievable power savings and service quality. Copyright © 2015 John Wiley & Sons, Ltd.

Research on Tailoring Technology of Array CCD Aerial Camera Linux System

In view of the actual demand of operating system of the air plane array CCD camera, and combining with the hardware resources of the PC104 bus structure, Linux system adopted in CCD camera is cut practically, which based on the tailoring method adopting the combination of coarse-grained and fine-grained to enhance the Linux kernel preemption, improve the scheduling strategy of Linux kernel scheduler, to build a embedded system with the strong implementation capacity. The system startup and task of the response performance test in different environment shows that the cut systems is stable, reliable, and can achieve the startup time less than 5s, the performance of the task response time less than 20 millisecond.

Effective Runtime Resource Management Using Linux Control Groups with the BarbequeRTRM Framework

The extremely high technology process reached by silicon manufacturing (smaller than 32nm) has led to production of computational platforms and SoC, featuring a considerable amount of resources. Whereas from one side such multi- and many-core platforms show growing performance capabilities, from the other side they are more and more affected by power, thermal, and reliability issues. Moreover, the increased computational capabilities allows congested usage scenarios with workloads subject to mixed and time-varying requirements. Effective usage of the resources should take into account both the application requirements and resources availability , with an arbiter, namely a resource manager in charge to solve the resource contention among demanding applications. Current operating systems (OS) have only a limited knowledge about application-specific behaviors and their time-varying requirements. Dedicated system interfaces to collect such inputs and forward them to the OS (e.g., its scheduler) are thus an interesting research area that aims at integrating the OS with an ad hoc resource manager. Such a component can exploit efficient low-level OS interfaces and mechanisms to extend its capabilities of controlling tasks and system resources. Because of the specific tasks and timings of a resource manager, this component can be easily and effectively developed as a user-space extension lying in between the OS and the controlled application. This article, which focuses on multicore Linux systems, shows a portable solution to enforce runtime resource management decisions based on the standard control groups framework. A burst and a mixed workload analysis, performed on a multicore-based NUMA platform, have reported some promising results both in terms of performance and power saving.

Infinite BusyBox with systemd

Build one Linux system within another, using the latest utilities within the systemd suite of management tools.

Design and Development of the Temperature Detection System

Mini2440 domestic microprocessor is used as the hardware platform and DS18B20 temperature sensor driver is developed through embedded Linux systems. BOA technology, CGI technology and network communication technology is used to achieve the hardware remote control. Through analysis of the demand for system functions, to achieve an effective detection and collection on the ambient temperature. The outcome is writing a program to implement the corresponding function of temperature data collection and through network to show and feedback the data of temperature.

Efficient hybrid-symbolic methods for quantum mechanical calculations

We present hybrid symbolic–numerical tools to generate optimized numerical code for rapid prototyping and fast numerical computation starting from a computer algebra system (CAS) and tailored to any given quantum mechanical problem. Although a major focus concerns the quantum chemistry methods of H. Nakatsuji which has yielded successful and very accurate eigensolutions for small atoms and molecules, the tools are general and may be applied to any basis set calculation with a variational principle applied to its linear and non-linear parameters. Program summaryProgram title: EVANCatalogue identifier: AEVU_v1_0Program summary URL:http://cpc.cs.qub.ac.uk/summaries/AEVU_v1_0.htmlProgram obtainable from: CPC Program Library, Queen’s University, Belfast, N. IrelandLicensing provisions: Standard CPC licence, http://cpc.cs.qub.ac.uk/licence/licence.htmlNo. of lines in distributed program, including test data, etc.: 99020No. of bytes in distributed program, including test data, etc.: 5388574Distribution format: tar.gzProgramming language: Maple[1], MATLAB, Scilab [2], FORTRAN.Computer: Ranging from laptop to CLUSTER system.Operating system: Linux system which supports Maple and MATLAB (or Scilab).RAM: 64 bytesClassification: 4, 5, 16.External routines: Macrofort[3,4], BLAS, LAPACK[5]Nature of problem: Develop and showcase general tools for analyzing and solving ab initio quantum chemistry problems, in particular an efficient means of generating an accurate and high performance optimized program for any specific problem.Solution method: Use a Computer Algebra system (CAS) to analyze any given problem, study its symmetries, explore basis sets that best match its natural properties, seek preliminary solutions and when needed, use hybrid symbolic–numerical tools to generate optimized code in MATLAB (or Scilab) or FORTRAN (or C), etc., code which is tailored to a specific problem combined with high-performance numerical routines for solving the given problem. Particular attention is spent on matrix elements for a resulting Hamiltonian and using accessible eigensolvers, as well as their accuracy and performance.Additional comments: Subroutines Generated by Maple or MacrofortRunning time: Variable depending on problem size and speed of processors but good algorithmic complexity

MathLibre

MathLibre is a project to archive free mathematical software and free mathematical documents and offer them on Live Linux system. MathLibre Project is the direct descendant of KNOPPIX/Math Project. It provides a desktop for mathematicians that can be set up easily and quickly.

Modification of Linux Kernel with JumpingVirtual Clock Round Robin Scheduling

The open-source software and free operating system has attracted the attention of many users. People have failed to notice that while installing regular distributions, user is often forced to install many programs which are probably never used. These programs waste resources. Additionally in Linux, the performed scheduling algorithms are with high complexity such as Weighted Fair Queuing. Unless one can change a Linux OS, one can’t avoid presence of components which will never be required. Linux From Scratch (LFS) system allows to create compact Linux systems. LFS guides for building Linux system, compiling and installing all packages one by one, setting up boot scripts and installing the kernel. Additionally process scheduling can be implemented to meet growing needs such as faster execution. Over LFS system, one can build a hybrid scheduling algorithm called Jumping Virtual Clock Round Robin algorithm which combines Dynamic JVC and Static RR to solve the problems present in existing Weighted Fair Queueing and Leaf Forward Virtual Clock algorithms.

The Transplantion and Realization of Qt4.7.0 Based on ARM9 and Linux

With continuous improvement and update of embedded Linux kernel, embedded technology has been widely used in handheld devices and industrial control field. Therefore, a user-friendly graphical user interface (GUI) is essential for these applications. This paper firstly presents the design method for transplanting Qt on embedded platform of ARM9. Secondly it elaborates the device driver development and Qt interface development in Linux system with a Qt test program. All transplantation method of Qt and test program have been tested and verified on the ARM9 platform.

Research of Network Camera Based on TMS320DM8168

The paper adopts the TMS320DM8168 processor to realize highly resolution network video surveillance system, and selects highly efficient video coding standard—H.264 compression algorithm to enhance the efficiency of coding data. The system based on embedded Linux system and the TMS320DM8168 processor is put forward which can be operated on 8-megapixel.At 60 frames per second in full frame rates, It is the video stream up to 2Mbps rate to provide resolution of 1920x1080 pixels. The Three video streams can be transferred in the 1000M Ethernet applied with the real time transport protocol (RTP) and real time transport control protocol (RTCP).

인공위성 탑재컴퓨터를 위한 리눅스 기반 ARINC 653 공간 분리

European Space Agency has recognized Integrated Modular Avionics and ARINC specification 653 as avionics computer system for space application. Integrated Modular Avionics specification reduces the space by integrating a system composed of many electronic devices into a computer. recent researches have been studying how to apply the ARINC 653 into an open source operating system, such as Linux. These studies have concentrated on partition scheduling for time separation. However, requirements to guarantee spatial separation should be further analyzed to ensure deterministic execution time. Therefore, memory management is needed to verify spatial isolation on Linux systems. This research proposes a new method to accomplish spatial isolation for the ARINC 653 specification in Linux. We have added new data structures and system calls to handle functionalities for spatial separation. They are used during the partition startup process. The proposed method was evaluated on the LEON4 processor, which is the next generation microprocessor to be used in the future space missions. All implementations confirm that spatial isolation of the ARINC 653 specification was accomplished.

Mass spectrometry-based protein identification with accurate statistical significance assignment.

Assigning statistical significance accurately has become increasingly important as metadata of many types, often assembled in hierarchies, are constructed and combined for further biological analyses. Statistical inaccuracy of metadata at any level may propagate to downstream analyses, undermining the validity of scientific conclusions thus drawn. From the perspective of mass spectrometry-based proteomics, even though accurate statistics for peptide identification can now be achieved, accurate protein level statistics remain challenging. We have constructed a protein ID method that combines peptide evidences of a candidate protein based on a rigorous formula derived earlier; in this formula the database P-value of every peptide is weighted, prior to the final combination, according to the number of proteins it maps to. We have also shown that this protein ID method provides accurate protein level E-value, eliminating the need of using empirical post-processing methods for type-I error control. Using a known protein mixture, we find that this protein ID method, when combined with the Sorić formula, yields accurate values for the proportion of false discoveries. In terms of retrieval efficacy, the results from our method are comparable with other methods tested. The source code, implemented in C++ on a linux system, is available for download at ftp://ftp.ncbi.nlm.nih.gov/pub/qmbp/qmbp_ms/RAId/RAId_Linux_64Bit.