Linux Networking Capabilities
explanatory Essay
619 words
Linux Networking Capabilities
Linux is a Unix clone written from scratch by Linus Torvalds with assistance from a loosely-knit team of hackers across the Net. It aims towards POSIX compliance. It has all the features expected in a modern fully-fledged Unix, including true multitasking, virtual memory, shared libraries, demand loading, shared copy-on-write executables, proper memory management and TCP/IP networking.
It runs mainly on 386/486/586-based PCs, using the hardware facilities of the 386-processor family to implement these features. Ports to other architectures are underway.
Linux is freely available, and no one is required to register their copies with any central authority, so it is difficult to know how many people use Linux. Several businesses are now surviving solely on selling and supporting Linux, and very few Linux users use those businesses, relatively speaking, and the Linux newsgroups are some of the most heavily read on the internet, so the number is likely in the hundreds of thousands, but hard numbers are hard to come by.
Linux Features
Multitasking. Several programs running at once.
Multiuser. Several users on the same machine at once. Two-user licenses are not possible.
Multiplatform. Runs on many different CPUs, not just Intel.
Multiprocessor. SMP support is available on the Intel and SPARC platforms (with work currently in progress on other platforms), and Linux is used in several loosely-coupled MP applications, including Beowulf systems and the Fujitsu AP1000+ SPARC-based supercomputer.
Runs in protected mode on the 386.
Memory protection between processes. So that one program can't bring the whole system down.
Demand loads executables. Linux only reads from disk those parts of a program that are actually used.
Shared copy-on-write pages among executables. This means that multiple process can use the same memory to run in. When one tries to write to that memory, that page (4KB piece of memory) is copied somewhere else. Copy-on-write has two benefits: increasing speed and decreasing memory use.
Virtual memory using paging (not swapping whole processes) to disk. To a separate partition or a file in the filesystem, or both, with the possibility of adding more swapping areas during runtime. A total of 16 of these 128 MB swapping areas can be used at once, for a theoretical total of 2 GB of useable swap space. It is simple to increase this if necessary, by changing a few lines of source code.
Unified memory pool for user programs and disk cache.
In this essay, the author
- Explains that linux is used in several loosely-coupled mp applications, including beowulf systems and the fujitsu ap1000+ sparc-based supercomputer.
- Explains that core dumps are used for post-mortem analysis, allowing the use of a debugger on programs not only while it is running but also after it has crashed.
- Describes linux as a unix clone written from scratch by linus torvalds with assistance from hackers across the net.
- Explains that linux only reads from disk parts of a program that are actually used. copy-on-write has two benefits: increasing speed and decreasing memory use.
- Explains that linux is compatible with sco, svr3, and s vr4 at the binary level. all source code is available, including the whole kernel and all drivers, development tools and user programs.
- Explains that every computer running linux appears to have a math coprocessor. if your computer already contains an fpu, it will be used instead of the emulation.
Related
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- Exploring Virtual Memoryexplanatory essayPaging is one of the memory-management schemes by which a computer can store and retrieve data from secondary storage for use in main memory. Paging is used for faster access to data. The paging memory-management scheme works by having the operating system retrieve data from the secondary storage in same-size blocks called pages. Paging writes data to secondary storage from main memory and also reads data from secondary storage to bring into main memory. The main advantage of paging over memory segmentation is that is allows the physical address space of a process to be noncontiguous. Before paging was implemented, systems had to fit whole programs into storage, contiguously, which would cause various storage problems and fragmentation inside the operating system (Belzer, Holzman, & Kent, 1981). Paging is a very important part of virtual memory impl...
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- Explains that virtual memory is a complex interrelationship between processor hardware and operating system software.
- Explains that paging is one of the memory-management schemes by which a computer can store and retrieve data from secondary storage for use in main memory.
- Explains that segmentation allows the programmer to view memory as consisting of multiple address space, or segments. segmentation simplifies the handling of growing data structures, and allows programs to be altered and recompiled independently.
- Explains that combined paging and segmentation have their strengths, and it is possible to develop sophisticated memory management algorithms that exploit the behavior of programs.
- Explains that each process has a segment table and page table associated with it.
- Explains that the performance of any particular set of policies depends on main memory size, relative speed of main and secondary memory, size and number of processes competing for resources, and execution behavior of individual programs.
- Explains that fetch policy determines when a page should be brought into main memory. there are two different ways of going about it: demand paging and prepaging.
- Explains that the placement policy determines where in real memory a process piece is to reside.
- Explains that the replacement policy uses basic algorithms to decide which pages to replace, such as optimal, least recently used, first-in-first-out, and clock.
- Explains that the cleaning policy is essentially the reverse of the fetch policy. it determines when modified pages should be written out of main memory and back into secondary memory.
- Explains how linux virtual memorylinux utilizes a three-level page table consisting of page directory, page middle directory and page tables.
- Explains that virtual memory allows for effective multiprogramming and relieves the user of the unnecessarily tight constraints of main memory.
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In this essay, the author
- Explains that there are a variety of unix versions that have been created. this article will focus on three of those versions including solaris, linux, and sunos.
- Explains that sun microsystems used solaris as the operating system that ran scalable processor architecture-based processors. sun had a lot of influence on the bigger unix workstation market.
- Explains that zfs, a combined file system and logical volume manager, was originally designed by sun microsystems.
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- Explains that linux, like opensolaris once was, is open source and provides its kernel as a platform for users to manipulate.
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- Explains that sunos is solaris' predecessor. it was unix's scalable processor architecture-based workstations and servers created by sun microsystems.
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- Explains that while transitioning from user mode to kernel mode, there may be system calls, interrupts and other exceptions.
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- Explains that system programs provide such software’s that users need not write their own programs to solve common problems.
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- Explains communications (system programs creating virtual connections between users, processors, and computer systems to transfer files from one system to another).
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- Explains that user can easily open and close directories or folders and delete unwanted files to improve system performance.
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In this essay, the author
- Explains that dos was bought from a seattle hacker by bill gates, for $50,000, and minix was developed by andrew s. tanenbaum to teach students the inner-workings of an operating system.
- Narrates how linus benedict torvalds spent most of his time toying with computer systems, trying to push their limits and increase their functionality. the key missing in his tests was an operating system with the flexibility craved by professionals.
- Describes how linus began developing an operating system that was a deviation for minix, using resources made available through the gnu project.
- Narrates how linus received an email from tanenbaum, stating that designing a monolithic kernel in 1991 was fundamentally wrong. he later admitted that this was not one of the high points in his o.s. design.
- Explains that as linux's popularity grew, commercial vendors began to snatch up the code. many companies like caldera, red-hat, suse, and debian put it in an easily distributable format.
- Explains that linux has been developed to be portable with palm pilots, and other chipsets. one distro was even designed with multi-processor computing in mind.
- Explains that linux is one of the best open source operating systems available, and many people swear by its name. linus torvalds is not rich like bill gates, a fact he is proud of.
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In this essay, the author
- Explains that the program will run itself in user mode because the application would start running at the lowest level which is ring 3.
- Explains that each memory goes through the memory management unit. the written code buffer is the piece of memory from translation lookaside buffer (tlb).
- Explains how the page table can hold multiple virtual page numbers. if there were 13 bits in a page number then 13 would be the amount that the operating system would rely on.
- Explains that switching from user to kernel mode requires a system call. the user mode executes the trap instruction.
- Explains that the os would have to use a soft link, which would parse the name of the path and be able to process it until it finds the correct one.
- Explains that the function open represents a file that was opened. the operating system makes several resources that are needed in order to access it.
- Explains that when the memory management unit performs the translation lookaide buffer (tlb), the os handles page fault by using data into the physical memory.
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In this essay, the author
- Describes how linux was founded by linus torvalds, a second-year computer science student in finland. he wanted an operating system similar to the unix system, but the hardware it ran on was excessively expensive.
- Describes how linus began to post his intentions and progress of his project on the internet and discovered that many programmers worldwide shared his interest.
- Explains that an operating system is software that is considered the backbone of a computer, managing both software and hardware resources.
- Explains that the operating system is not merely one program as it consists of many smaller programs and utilities that allow the user to run other programs on top of it.
- Explains that the kernel is the lowest level of software that interfaces with the hardware in a computer. in unix, users typically have no direct access to it.
- Explains that linux kernel developers designed kernel modules that could be loaded and unloaded at runtime. a kernel is essential for any computer system to run and operate properly.
- Explains that torvalds remains the definitive authority on what new codes are incorporated into the linux kernel. linux distribution modifies the kernel according to each user’s requirements.
- Explains that backtrack linux is a custom, security testing distribution designed for many different skill levels. its main purpose is to test networks, devices, and systems for security vulnerabilities.
- Explains that open source software and applications are developed by many programmers around the world who contribute their time in order to help everyone gain access to the greatest software.
- Explains richard stallman's idea and development of creating a free operating system was first established by the gnu project in the early 1980s.
- Explains that linus torvalds, an innovative finnish student, wrote an open source kernel named linux.
- Explains that linux is licensed under the general public license (gpl), which ensures that the software will continuously be open to anyone. torvalds holds the linux trademark, and actively monitors the use of it.
- Explains that linux has a single hierarchal directory structure. everything starts from the root directory, and then expands into sub-directories.
- Explains that linux, as well as most of its drivers, is written in c language using gnu/gcc compiler set.
- Explains that linux doesn't know of partitions or devices unless you mount a partition or device. the unified file system offers several advantages over windows and other similar systems.
- Explains that linux is one of the fastest growing operating systems in history, completing a decade of development. its most notable use is in the field of massively parallel supercomputing clusters.
- Compares linux desktop market share to microsoft's lucrative operating systems. linux has a larger share in servers, netbooks, and embedded devices.
- Explains that linux, and other related open source products can be scaled to run in almost any computer with very few resources. they have become a suitable alternative for low budget computer users.
- Explains that linux is a worldwide distribution bringing together huge companies and millions of people who support open source software. linus torvalds's interest and passion for computer science gave birth to linux.
1496 wordsRead More - Operating System Proposal: Linuxexplanatory essayOperating System Proposal Linux has long been one of many operating systems that have been out to prove its worth in all types of environment. It is currently being considered for enterprise network purposes as well as data centers where it implies servers, workstations and any mainframes as needed. Choosing what operating system to use, whether it is open source or not, can be difficult, though. This paper projects the advantages and concerns of choosing an open source solution like Linux as administrators and users are becoming more aware of Linux running on both server and desktop systems. It is quickly being adopted in an ever increasing number of global corporations and government agencies.
In this essay, the author
- Explains that this report is intended to provide an objective review of where and how linux might fit into your business related plans and activities moving forward.
- Cites petersen, r. (2004). red hat: the complete reference enterprise linux & fedora edition.
- Explains that red hat enterprise linux anticipates shifts in the it landscape that blur the lines between physical, virtual, and cloud computing.
- Explains that red hat enterprise linux can help your organization flexibly and seamlessly transition to your next-generation datacenter model.
- Opines that fedora is the fastest-developing, cutting edge linux system, compared with the stable, less-often-updated red hat enterprise linux.
- Explains that suse is one of the fastest growing distributions worldwide. it is the first company to market linux for the enterprise.
- Explains that some popular network applications are specifically designed to deliver information from one system to another.
- Describes electronic mail (e-mail) that you use to send messages to any other person on the internet using addresses like joe@someplace.com.
- Describes sendmail as a mail server for exchanging e-mail messages between systems using smtp (simple mail transfer protocol).
- Describes apache web server for sending documents from one system to another using http (hypertext transfer protocol).
- Describes the ftp server for transferring files between computers on the internet.
- Opines that while we cannot infer overall mainstream penetration or trends from a study like this based on feedback from existing adopters, it is clear that some maturing is taking place in the whole desktop linux arena.
- Explains haddad, i., and petersen, r. getting started with red hat linux.
- Cites petersen, r. (2004). red hat: the complete reference enterprise linux & fedora edition.
- Explains the advantages and concerns of choosing an open source solution like linux as administrators and users are becoming more aware of it running on both server and desktop systems.
- Explains that linux enjoys the industry's most avid user base. the major factors leading businesses to move to linux are its low cost, security, reliability, openness, and freedom to avoid single-vendor environments.
- Explains that red hat linux is the first and most well-known linux distribution in most businesses now-a-days.
- Explains that linux contains a full set of internet clients and servers including mail, news, ftp, and web, as well as proxy clients.
- Explains that red hat offers several commercial products and services for business and e-commerce solutions, including the interchange e-commerce platform, stronghold secure server, and credit card verification service.
- Describes fedora as a community-driven, rapid development operating system that was distributed for free (as is) every six to nine months.
- Explains that a suse linux os can offer remote login to connect to and work with another computer on the internet — assuming you have the required username and password.
2377 wordsRead More