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FreeBSD Jail
The jail mechanism is an implementation of FreeBSD's OS-level virtualisation that allows system administrators to partition a FreeBSD-derived computer system into several independent mini-systems called ''jails'', all sharing the same kernel, with very little overhead. It is implemented through a system call, jail(2), as well as a userland utility, jail(8), plus, depending on the system, a number of other utilities. The functionality was committed into FreeBSD in 1999 by Poul-Henning Kamp after some period of production use by a hosting provider, and was first released with FreeBSD 4.0, thus being supported on a number of FreeBSD descendants, including DragonFly BSD, to this day. History The need for the FreeBSD jails came from a small shared-environment hosting provider's (R&D Associates, Inc.'s owner, Derrick T. Woolworth) desire to establish a clean, clear-cut separation between their own services and those of their customers, mainly for security and ease of administrationjail( ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
FreeBSD
FreeBSD is a free and open-source Unix-like operating system descended from the Berkeley Software Distribution (BSD), which was based on Research Unix. The first version of FreeBSD was released in 1993. In 2005, FreeBSD was the most popular open-source BSD operating system, accounting for more than three-quarters of all installed and permissively licensed BSD systems. FreeBSD has similarities with Linux, with two major differences in scope and licensing: FreeBSD maintains a complete system, i.e. the project delivers a kernel, device drivers, userland utilities, and documentation, as opposed to Linux only delivering a kernel and drivers, and relying on third-parties for system software; FreeBSD source code is generally released under a permissive BSD license, as opposed to the copyleft GPL used by Linux. The FreeBSD project includes a security team overseeing all software shipped in the base distribution. A wide range of additional third-party applications may be i ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Computer Cluster
A computer cluster is a set of computers that work together so that they can be viewed as a single system. Unlike grid computers, computer clusters have each node set to perform the same task, controlled and scheduled by software. The components of a cluster are usually connected to each other through fast local area networks, with each node (computer used as a server) running its own instance of an operating system. In most circumstances, all of the nodes use the same hardware and the same operating system, although in some setups (e.g. using Open Source Cluster Application Resources (OSCAR)), different operating systems can be used on each computer, or different hardware. Clusters are usually deployed to improve performance and availability over that of a single computer, while typically being much more cost-effective than single computers of comparable speed or availability. Computer clusters emerged as a result of convergence of a number of computing trends including t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Prentice Hall Professional
Prentice Hall was an American major educational publisher owned by Savvas Learning Company. Prentice Hall publishes print and digital content for the 6–12 and higher-education market, and distributes its technical titles through the Safari Books Online e-reference service. History On October 13, 1913, law professor Charles Gerstenberg and his student Richard Ettinger founded Prentice Hall. Gerstenberg and Ettinger took their mothers' maiden names, Prentice and Hall, to name their new company. Prentice Hall became known as a publisher of trade books by authors such as Norman Vincent Peale; elementary, secondary, and college textbooks; loose-leaf information services; and professional books. Prentice Hall acquired the training provider Deltak in 1979. Prentice Hall was acquired by Gulf+Western in 1984, and became part of that company's publishing division Simon & Schuster. S&S sold several Prentice Hall subsidiaries: Deltak and Resource Systems were sold to National Educatio ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hypervisor
A hypervisor (also known as a virtual machine monitor, VMM, or virtualizer) is a type of computer software, firmware or hardware that creates and runs virtual machines. A computer on which a hypervisor runs one or more virtual machines is called a ''host machine'', and each virtual machine is called a ''guest machine''. The hypervisor presents the guest operating systems with a virtual operating platform and manages the execution of the guest operating systems. Unlike an emulator, the guest executes most instructions on the native hardware. Multiple instances of a variety of operating systems may share the virtualized hardware resources: for example, Linux, Windows, and macOS instances can all run on a single physical x86 machine. This contrasts with operating-system–level virtualization, where all instances (usually called ''containers'') must share a single kernel, though the guest operating systems can differ in user space, such as different Linux distributions with the sa ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Vnet
VNET is an international computer networking system deployed in the mid-1970s and still in current, but highly diminished use. It was developed inside IBM and provided the main email and file-transfer backbone for the company throughout the 1980s and 1990s. Through it, a number of protocols were developed to deliver email amongst time sharing computers over alternative transmission systems. VNET was first deployed as a private host to host network among CP/67 and VM/370 mainframes beginning before 1975. It was based on RSCS, a virtual machine–based communications program and an inter machine protocol developed in IBM's Advanced Systems Development Division's Remote Service System (RSS) prototype which produced some of the technology in the IBM Tivoli Software, Tivoli product. RSCS used the Binary Synchronous Communications (BSC) protocol, not SNA/SDLC, to support file to file transfer among virtual machine users. The first several nodes included Scientific Centers and Poughkeepsie, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Vkernel
A virtual kernel architecture (vkernel) is an operating system virtualisation paradigm where kernel code can be compiled to run in the user space, for example, to ease debugging of various kernel-level components, in addition to general-purpose virtualisation and compartmentalisation of system resources. It is used by DragonFly BSD in its vkernel implementation since DragonFly 1.7, having been first revealed in , and first released in the stable branch with DragonFly 1.8 in . The long-term goal, in addition to easing kernel development, is to make it easier to support internet-connected computer clusters without compromising local security. Similar concepts exist in other operating systems as well; in Linux, a similar virtualisation concept is known as user-mode Linux; whereas in NetBSD since the summer of 2007, it has been the initial focus of the rump kernel infrastructure. The ''virtual kernel'' concept is nearly the exact opposite of the '' unikernel'' concept — with ''vk ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Bhyve
bhyve (pronounced "bee hive", formerly written as BHyVe for "BSD hypervisor") is a type-2 hypervisor initially written for FreeBSD. It can also be used on a number of illumos based distributions including SmartOS, OpenIndiana, and OmniOS. A port of bhyve to macOS called xhyve is also available. Features bhyve supports the virtualization of several guest operating systems, including FreeBSD 9+, OpenBSD, NetBSD, Linux, illumos, DragonFly and Windows NT (Windows Vista and later, Windows Server 2008 and later). bhyve also supports UEFI installations and VirtIO emulated interfaces. Windows virtual machines require VirtIO drivers for a stable operation. Current development efforts aim at widening support for other operating systems for the x86-64 architecture. Support for peripherals relies on basic and VirtIO drivers and supports: eXtensible Host Controller Interface (xHCI) USB controllers, NVM Express (NVMe) controllers, High Definition Audio Controllers, raw framebuffer de ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Chroot
A chroot on Unix and Unix-like operating systems is an operation that changes the apparent root directory for the current running process and its children. A program that is run in such a modified environment cannot name (and therefore normally cannot access) files outside the designated directory tree. The term "chroot" may refer to the system call or the wrapper program. The modified environment is called a chroot jail. History The chroot system call was introduced during development of Version 7 Unix in 1979. One source suggests that Bill Joy added it on 18 March 1982 – 17 months before 4.2BSD was released – in order to test its installation and build system. All versions of BSD that had a kernel have chroot(2). An early use of the term "jail" as applied to chroot comes from Bill Cheswick creating a honeypot to monitor a hacker in 1991. The first article about a jailbreak has been discussed on the security column of SunWorld Online which is written by Car ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Operating System-level Virtualization
OS-level virtualization is an operating system (OS) paradigm in which the kernel allows the existence of multiple isolated user space instances, called ''containers'' ( LXC, Solaris containers, Docker, Podman), ''zones'' (Solaris containers), ''virtual private servers'' ( OpenVZ), ''partitions'', ''virtual environments'' (VEs), ''virtual kernels'' (DragonFly BSD), or ''jails'' (FreeBSD jail or chroot jail). Such instances may look like real computers from the point of view of programs running in them. A computer program running on an ordinary operating system can see all resources (connected devices, files and folders, network shares, CPU power, quantifiable hardware capabilities) of that computer. However, programs running inside of a container can only see the container's contents and devices assigned to the container. On Unix-like operating systems, this feature can be seen as an advanced implementation of the standard chroot mechanism, which changes the apparent root folde ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Comparison Of Platform Virtualization Software
Platform virtualization software, specifically emulators and hypervisors, are software packages that emulate the whole physical computer machine, often providing multiple virtual machines on one physical platform. The table below compares basic information about platform virtualization hypervisors. General Features * Providing any virtual environment usually requires some overhead of some type or another. Native usually means that the virtualization technique does not do any CPU level virtualization (like Bochs), which executes code more slowly than when it is directly executed by a CPU. Some other products such as VMware and Virtual PC use similar approaches to Bochs and QEMU, however they use a number of advanced techniques to shortcut most of the calls directly to the CPU (similar to the process that JIT compiler uses) to bring the speed to near native in most cases. However, some products such as coLinux, Xen, z/VM (in real mode) do not suffer the cost of CPU-level sl ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Mount (computing)
Mounting is a process by which a computer's operating system makes files and directories on a storage device (such as hard drive, CD-ROM, or network share) available for users to access via the computer's file system. In general, the process of mounting comprises the operating system acquiring access to the storage medium; recognizing, reading, and processing file system structure and metadata on it before registering them to the virtual file system (VFS) component. The location in the VFS to which the newly mounted medium was registered is called a mount point; when the mounting process is completed, the user can access files and directories on the medium from there. An opposite process of mounting is called unmounting, in which the operating system cuts off all user access to files and directories on the mount point, writes the remaining queue of user data to the storage device, refreshes file system metadata, then relinquishes access to the device, making the storage devic ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Routing Table
In computer networking, a routing table, or routing information base (RIB), is a data table stored in a router or a network host that lists the routes to particular network destinations, and in some cases, metrics (distances) associated with those routes. The routing table contains information about the topology of the network immediately around it. The construction of routing tables is the primary goal of routing protocols. Static routes are entries that are fixed, rather than resulting from routing protocols and network topology discovery procedures. Overview A routing table is analogous to a distribution map in package delivery. Whenever a node needs to send data to another node on a network, it must first know ''where'' to send it. If the node cannot directly connect to the destination node, it has to send it via other nodes along a route to the destination node. Each node needs to keep track of which way to deliver various packages of data, and for this it uses a routing ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
