Chrony
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Chrony
chrony is an implementation of the Network Time Protocol (NTP). It's an alternative to ntpd, which is a reference implementation of NTP. It runs on Unix-like operating systems (including Linux and macOS) and is released under the GNU GPL v2. It's the default NTP client and server in Red Hat Enterprise Linux 8 and SUSE Linux Enterprise Server 15, and available in many Linux distributions. Support for Network Time Security (NTS) was added on version 4.0. Comparison with the reference implementation In contrast to NTPsec, which is a security-focused fork of ntpd, chrony was implemented from scratch. It was designed to synchronize time even in difficult conditions such as intermittent network connections (such as laptops) and congested networks. Some improvements in this regard (compared to reference ntpd) include that it never steps (abruptly adjusts) time outside of startup, can correct for asymmetric network jitters, and can use larger clock rate adjustments on Linux to deal ...
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Network Time Protocol
The Network Time Protocol (NTP) is a networking protocol for clock synchronization between computer systems over packet-switched, variable- latency data networks. In operation since before 1985, NTP is one of the oldest Internet protocols in current use. NTP was designed by David L. Mills of the University of Delaware. NTP is intended to synchronize all participating computers to within a few milliseconds of Coordinated Universal Time (UTC). It uses the intersection algorithm, a modified version of Marzullo's algorithm, to select accurate time servers and is designed to mitigate the effects of variable network latency. NTP can usually maintain time to within tens of milliseconds over the public Internet, and can achieve better than one millisecond accuracy in local area networks under ideal conditions. Asymmetric routes and network congestion can cause errors of 100 ms or more. The protocol is usually described in terms of a client–server model, but can as easily be ...
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Ntpd
The Network Time Protocol daemon (ntpd) is an operating system program that maintains the system time in synchronization with time servers using the Network Time Protocol (NTP). Description The ntpd program is an operating-system daemon that sets and maintains a computer system's system time in synchronization with Internet-standard time servers. It is a complete implementation of the Network Time Protocol (NTP) version 4, but retains compatibility with versions 1, 2, and 3 as defined by RFC 1059, RFC 1119, and RFC 1305, respectively. ntpd performs most computations in 64-bit floating point arithmetic and uses 64-bit fixed point operations only when necessary to preserve the ultimate precision, about 232 picoseconds. While ordinary workstations and networks cannot achieve the ultimate precision , future processors and networks may require it. xntpd is the Network Time Protocol version three (1992) daemon software. The "x" was added to the name because the branch of code that eve ...
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Red Hat
Red Hat, Inc. is an American software company that provides open source software products to enterprises. Founded in 1993, Red Hat has its corporate headquarters in Raleigh, North Carolina, with other offices worldwide. Red Hat has become associated to a large extent with its enterprise operating system Red Hat Enterprise Linux. With the acquisition of open-source enterprise middleware vendor JBoss, Red Hat also offers Red Hat Virtualization (RHV), an enterprise virtualization product. Red Hat provides storage, operating system platforms, middleware, applications, management products, and support, training, and consulting services. Red Hat creates, maintains, and contributes to many free software projects. It has acquired several proprietary software product codebases through corporate mergers and acquisitions and has released such software under open source licenses. , Red Hat is the second largest corporate contributor to the Linux kernel version 4.14 after Intel. On Octob ...
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SUSE Linux Enterprise Server
SUSE Linux Enterprise (often abbreviated to SLE) is a Linux-based operating system developed by SUSE. It is available in two editions, suffixed with Server (SLES) for servers and mainframes, and Desktop (SLED) for workstations and desktop computers. Its major versions are released at an interval of 3–4 years, while minor versions (called "Service Packs") are released about every 12 months. SUSE Linux Enterprise products receive more intense testing than the upstream openSUSE community product, with the intention that only mature, stable versions of the included components will make it through to the released enterprise product. It is developed from a common code base with other SUSE Linux Enterprise products. IBM's Watson was built on IBM's POWER7 systems using SLES. In March 2018, SUSE Product Manager Jay Kruemcke wrote in SUSE blog that SUSE Linux Enterprise developers have ported it to Raspberry Pi. SUSE Linux Enterprise Server SLES was developed based on SUSE Linux by ...
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Network Time-related Software
Network, networking and networked may refer to: Science and technology * Network theory, the study of graphs as a representation of relations between discrete objects * Network science, an academic field that studies complex networks Mathematics * Networks, a graph with attributes studied in network theory ** Scale-free network, a network whose degree distribution follows a power law ** Small-world network, a mathematical graph in which most nodes are not neighbors, but have neighbors in common * Flow network, a directed graph where each edge has a capacity and each edge receives a flow Biology * Biological network, any network that applies to biological systems * Ecological network, a representation of interacting species in an ecosystem * Neural network, a network or circuit of neurons Technology and communication * Artificial neural network, a computing system inspired by animal brains * Broadcast network, radio stations, television stations, or other electronic media outlets ...
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OpenNTPD
OpenNTPD (also known as OpenBSD NTP Daemon) is a Unix daemon implementing the Network Time Protocol to synchronize the local clock of a computer system with remote NTP servers. It is also able to act as an NTP server to NTP-compatible clients. OpenBSD NTP Daemon was initially developed by Alexander Guy and Henning Brauer as part of the OpenBSD project, with further help by many authors. Its design goals include being secure ( non-exploitable), easy to configure, and accurate enough for most purposes. Its portable version, like that of OpenSSH, is developed as a child project which adds the portability code to the OpenBSD version and releases it separately. The portable version is developed by Brent Cook. The project developers receive some funding from the OpenBSD Foundation. History The development of OpenNTPD was motivated by a combination of issues with current NTP daemons: difficult configuration, complicated and difficult to audit code, and unsuitable licensing. OpenNT ...
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Multicast
In computer networking, multicast is group communication where data transmission is addressed to a group of destination computers simultaneously. Multicast can be one-to-many or many-to-many distribution. Multicast should not be confused with physical layer point-to-multipoint communication. Group communication may either be application layer multicast or network-assisted multicast, where the latter makes it possible for the source to efficiently send to the group in a single transmission. Copies are automatically created in other network elements, such as routers, switches and cellular network base stations, but only to network segments that currently contain members of the group. Network assisted multicast may be implemented at the data link layer using one-to-many addressing and switching such as Ethernet multicast addressing, Asynchronous Transfer Mode (ATM), point-to-multipoint virtual circuits (P2MP) or InfiniBand multicast. Network-assisted multicast may also be impl ...
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Precision Time Protocol
The Precision Time Protocol (PTP) is a protocol used to synchronize clocks throughout a computer network. On a local area network, it achieves clock accuracy in the sub-microsecond range, making it suitable for measurement and control systems. PTP is employed to synchronize financial transactions, mobile phone tower transmissions, sub-sea acoustic arrays, and networks that require precise timing but lack access to satellite navigation signals. The first version of PTP, IEEE 1588-2002, was published in 2002. IEEE 1588-2008, also known as PTP Version 2 is not backward compatible with the 2002 version. IEEE 1588-2019 was published in November 2019 and includes backward-compatible improvements to the 2008 publication. IEEE 1588-2008 includes a ''profile'' concept defining PTP operating parameters and options. Several profiles have been defined for applications including telecommunications, electric power distribution and audiovisual. is an adaptation of PTP for use with Audio Vid ...
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Local Area Network
A local area network (LAN) is a computer network that interconnects computers within a limited area such as a residence, school, laboratory, university campus or office building. By contrast, a wide area network (WAN) not only covers a larger geographic distance, but also generally involves leased telecommunication circuits. Ethernet and Wi-Fi are the two most common technologies in use for local area networks. Historical network technologies include ARCNET, Token Ring and AppleTalk. History The increasing demand and usage of computers in universities and research labs in the late 1960s generated the need to provide high-speed interconnections between computer systems. A 1970 report from the Lawrence Radiation Laboratory detailing the growth of their "Octopus" network gave a good indication of the situation. A number of experimental and early commercial LAN technologies were developed in the 1970s. Cambridge Ring was developed at Cambridge University starting in 1974. Ethe ...
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Laptops
A laptop, laptop computer, or notebook computer is a small, portable personal computer (PC) with a screen and alphanumeric keyboard. Laptops typically have a clam shell form factor with the screen mounted on the inside of the upper lid and the keyboard on the inside of the lower lid, although 2-in-1 PCs with a detachable keyboard are often marketed as laptops or as having a "laptop mode". Laptops are folded shut for transportation, and thus are suitable for mobile use. They are so named because they can be practically placed on a person's lap when being used. Today, laptops are used in a variety of settings, such as at work, in education, for playing games, web browsing, for personal multimedia, and for general home computer use. As of 2022, in American English, the terms ''laptop computer'' and ''notebook computer'' are used interchangeably; in other dialects of English, one or the other may be preferred. Although the terms ''notebook computers'' or ''notebooks'' or ...
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Linux Distributions
A Linux distribution (often abbreviated as distro) is an operating system made from a software collection that includes the Linux kernel and, often, a package management system. Linux users usually obtain their operating system by downloading one of the Linux distributions, which are available for a wide variety of systems ranging from embedded devices (for example, OpenWrt) and personal computers (for example, Linux Mint) to powerful supercomputers (for example, Rocks Cluster Distribution). A typical Linux distribution comprises a Linux kernel, GNU tools and libraries, additional software, documentation, a window system (the most common being the X Window System, or, more recently, Wayland), a window manager, and a desktop environment. Most of the included software is free and open-source software made available both as compiled binaries and in source code form, allowing modifications to the original software. Usually, Linux distributions optionally include some proprietary sof ...
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