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A headless computer is a computer system or device that has been configured to operate without a monitor (the missing "head"), keyboard, and mouse. A headless system is typically controlled over a network connection, although some headless system devices require a serial connection to be made over RS-232 for administration of the device. Headless operation of a server is typically employed to reduce operating costs. [1]
During bootup, some (especially older) PC BIOS versions will wait indefinitely for a user to press a key before proceeding. If some basic device, such as a video card or keyboard, are not installed or connected, this could effectively halt an unattended system.
On more modern systems, the BIOS factory setting will typically be configured to behave this way as well, but this setting can be changed with a BIOS setup utility to proceed without user intervention.
Even in cases where a system has been set up to be managed remotely, a local keyboard and video card may still be needed from time to time; for example, to diagnose boot problems that occur before a remote access application is initialized.
Some servers provide for remote control with an internal network card and hardware that mirrors the console screen. For example, HP offers a system called Integrated Lights-Out (iLO) that provides this function. [2] Remote access to the system is gained using a secure web connection to an IP address assigned to the iLO adapter, and allows for monitoring of the system during start-up, before the operating system is loaded.
Another hardware solution is to use a KVM-over-IP switch. Such a switch is a traditional Keyboard-Video-Mouse device with the added ability to provide remote control sessions over IP. [3] Connection to the KVM device is gained using a web browser, which allows for remote monitoring of the connected system console port.
Administration of a headless system typically takes place with a text-based interface such as a command line in Unix or in Linux. These interfaces, often called "virtual terminals" or "terminal emulators", attempt to simulate the behavior of "real" interface terminals like the Digital Equipment Corporation's VT100, but over networks, usually using protocols such as Secure Shell.
One can also use systems such as X Window System and VNC combined with virtual display drivers - this setup allows remote connections to headless machines through ordinary graphical user interfaces, often running over network protocols like TCP/IP.
Wake-on-LAN is an Ethernet or Token Ring computer networking standard that allows a computer to be turned on or awakened from sleep mode by a network message.
A terminal emulator, or terminal application, is a computer program that emulates a video terminal within some other display architecture. Though typically synonymous with a shell or text terminal, the term terminal covers all remote terminals, including graphical interfaces. A terminal emulator inside a graphical user interface is often called a terminal window.
One meaning of system console, computer console, root console, operator's console, or simply console is the text entry and display device for system administration messages, particularly those from the BIOS or boot loader, the kernel, from the init system and from the system logger. It is a physical device consisting of a keyboard and a screen, and traditionally is a text terminal, but may also be a graphical terminal. System consoles are generalized to computer terminals, which are abstracted respectively by virtual consoles and terminal emulators. Today communication with system consoles is generally done abstractly, via the standard streams, but there may be system-specific interfaces, for example those used by the system kernel.
A remote access service (RAS) is any combination of hardware and software to enable the remote access tools or information that typically reside on a network of IT devices.
An output device is any piece of computer hardware that converts information into a human-perceptible form or, historically, into a physical machine-readable form for use with other non-computerized equipment. It can be text, graphics, tactile, audio, or video. Examples include monitors, printers, speakers, headphones, projectors, GPS devices, optical mark readers, and braille readers.
A KVM switch is a hardware device that allows a user to control multiple computers from one or more sets of keyboards, video monitors, and mice.
x11vnc is a Virtual Network Computing (VNC) server program. It allows remote access from a remote client to a computer hosting an X Window session and the x11vnc software, continuously polling the X server's frame buffer for changes. This allows the user to control their X11 desktop from a remote computer either on the user's own network, or from over the Internet as if the user were sitting in front of it. x11vnc can also poll non-X11 frame buffer devices, such as webcams or TV tuner cards, iPAQ, Neuros OSD, the Linux console, and the Mac OS X graphics display. x11vnc is part of the LibVNCServer project and is free software available under the GNU General Public License. x11vnc was written by Karl Runge.
NX technology, commonly known as NX or NoMachine, is a remote access and remote control computer software, allowing remote desktop access and maintenance of computers. It is developed by the Luxembourg-based company NoMachine S.à r.l.. NoMachine is proprietary software and is free-of-charge for non-commercial use.
QEMU is a free and open-source emulator. It emulates the machine's processor through dynamic binary translation and provides a set of different hardware and device models for the machine, enabling it to run a variety of guest operating systems. It can interoperate with Kernel-based Virtual Machine (KVM) to run virtual machines at near-native speed. QEMU can also do emulation for user-level processes, allowing applications compiled for one architecture to run on another.
Remote administration refers to any method of controlling a computer from a remote location. Software that allows remote administration is becoming increasingly common and is often used when it is difficult or impractical to be physically near a system in order to use it. A remote location may refer to a computer in the next room or one on the other side of the world. It may also refer to both legal and illegal remote administration.
A terminal server connects devices with a serial port to a local area network (LAN). Products marketed as terminal servers can be very simple devices that do not offer any security functionality, such as data encryption and user authentication. The primary application scenario is to enable serial devices to access network server applications, or vice versa, where security of the data on the LAN is not generally an issue. There are also many terminal servers on the market that have highly advanced security functionality to ensure that only qualified personnel can access various servers and that any data that is transmitted across the LAN, or over the Internet, is encrypted. Usually, companies that need a terminal server with these advanced functions want to remotely control, monitor, diagnose and troubleshoot equipment over a telecommunications network.
The Intelligent Platform Management Interface (IPMI) is a set of computer interface specifications for an autonomous computer subsystem that provides management and monitoring capabilities independently of the host system's CPU, firmware and operating system. IPMI defines a set of interfaces used by system administrators for out-of-band management of computer systems and monitoring of their operation. For example, IPMI provides a way to manage a computer that may be powered off or otherwise unresponsive by using a network connection to the hardware rather than to an operating system or login shell. Another use case may be installing a custom operating system remotely. Without IPMI, installing a custom operating system may require an administrator to be physically present near the computer, insert a DVD or a USB flash drive containing the OS installer and complete the installation process using a monitor and a keyboard. Using IPMI, an administrator can mount an ISO image, simulate an installer DVD, and perform the installation remotely.
The Dell Remote Access Controller (DRAC) is an out-of-band management platform on certain Dell servers. The platform may be provided on a separate expansion card, or integrated into the main board; when integrated, the platform is referred to as iDRAC.
A multiseat, multi-station or multiterminal system is a single computer which supports multiple independent local users at the same time.
In systems management, out-of-band management involves the use of management interfaces for managing networking equipment. Out-of-band (OOB) management is a networking term which refers to accessible and managing network infrastructure at remote locations, and doing it through a separate management plane from the production network. Cellular 4G and 5G networks are used today for out-of-band management and many manufacturers have it as a product offering. Out-of-band management is now considered an essential network component to ensure business continuity.
A home server is a computing server located in a private computing residence providing services to other devices inside or outside the household through a home network or the Internet. Such services may include file and printer serving, media center serving, home automation control, web serving, web caching, file sharing and synchronization, video surveillance and digital video recorder, calendar and contact sharing and synchronization, account authentication, and backup services. In the recent times, it has become very common to run literally hundreds of applications as containers, isolated from the host operating system.
In computing, the term remote desktop refers to a software- or operating system feature that allows a personal computer's desktop environment to be run remotely off of one system, while being displayed on a separate client device. Remote desktop applications have varying features. Some allow attaching to an existing user's session and "remote controlling", either displaying the remote control session or blanking the screen. Taking over a desktop remotely is a form of remote administration.
Intel Active Management Technology (AMT) is hardware and firmware for remote out-of-band management of select business computers, running on the Intel Management Engine, a microprocessor subsystem not exposed to the user, intended for monitoring, maintenance, updating, and repairing systems. Out-of-band (OOB) or hardware-based management is different from software-based management and software management agents.
Remote Desktop Services (RDS), known as Terminal Services in Windows Server 2008 and earlier, is one of the components of Microsoft Windows that allow a user to initiate and control an interactive session on a remote computer or virtual machine over a network connection. RDS was first released in 1998 as Terminal Server in Windows NT 4.0 Terminal Server Edition, a stand-alone edition of Windows NT 4.0 Server that allowed users to log in remotely. Starting with Windows 2000, it was integrated under the name of Terminal Services as an optional component in the server editions of the Windows NT family of operating systems, receiving updates and improvements with each version of Windows. Terminal Services were then renamed to Remote Desktop Services with Windows Server 2008 R2 in 2009.
The Linux console is a system console internal to the Linux kernel. A system console is the device which receives all kernel messages and warnings and which allows logins in single user mode. The Linux console provides a way for the kernel and other processes to send text output to the user, and to receive text input from the user. The user typically enters text with a computer keyboard and reads the output text on a computer monitor. The Linux kernel supports virtual consoles – consoles that are logically separate, but which access the same physical keyboard and display. The Linux console are implemented by the VT subsystem of the Linux kernel, and do not rely on any user space software. This is in contrast to a terminal emulator, which is a user space process that emulates a terminal, and is typically used in a graphical display environment.