Console server
Encyclopedia
A console server is a device or service that provides access to the system console
of a computing device via networking technologies.
Most commonly, a console server provides a number of serial port
s, which are then connected to the serial ports of other equipment, such as servers, routers or switches. The consoles of the connected devices can then be accessed by connecting to the console server over a serial link such as a modem
, or over a network with terminal emulator
software such as telnet
or ssh
, maintaining survivable connectivity that allows remote users to log in the various consoles without being physically nearby.
Some users have created their own console servers using off-the-shelf commodity computer hardware, usually with multiport serial cards typically running a slimmed-down Unix-like
operating system such as Linux
. Such "home-grown" console servers can be less expensive, especially if built from components that have been retired in upgrades, and allow greater flexibility by putting full control of the software driving the device in the hands of the administrator. This includes full access to and configurability of a wide array of security protocols and encryption standards, making it possible to create a console server that is more secure. However, this solution may have a higher TCO
, less reliability and higher rack-space requirements, since most industrial console servers have the physical dimension of one rack unit
(1U), whereas a desktop computer with full-size PCI
cards requires at least 3Us, making the home-grown solution more costly in the case of a co-located
infrastructure.
An alternative approach to a console server used in some cluster setups is to null-modem wire and daisy-chain consoles to otherwise unused serial ports on nodes with some other primary function.
System console
The system console, root 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...
of a computing device via networking technologies.
Most commonly, a console server provides a number of serial port
Serial port
In computing, a serial port is a serial communication physical interface through which information transfers in or out one bit at a time...
s, which are then connected to the serial ports of other equipment, such as servers, routers or switches. The consoles of the connected devices can then be accessed by connecting to the console server over a serial link such as a modem
Modem
A modem is a device that modulates an analog carrier signal to encode digital information, and also demodulates such a carrier signal to decode the transmitted information. The goal is to produce a signal that can be transmitted easily and decoded to reproduce the original digital data...
, or over a network with terminal emulator
Terminal emulator
A terminal emulator, terminal application, term, or tty for short, is a program that emulates a video terminal within some other display architecture....
software such as telnet
TELNET
Telnet is a network protocol used on the Internet or local area networks to provide a bidirectional interactive text-oriented communications facility using a virtual terminal connection...
or ssh
Secure Shell
Secure Shell is a network protocol for secure data communication, remote shell services or command execution and other secure network services between two networked computers that it connects via a secure channel over an insecure network: a server and a client...
, maintaining survivable connectivity that allows remote users to log in the various consoles without being physically nearby.
Description
Dedicated console server appliances are available from a number of manufacturers in many configurations, with the number of serial ports ranging from one to 48. These Console Servers are primarily used for secure remote access to Unix Servers, Linux Servers, Windows Servers and any device on the network with a console port. The purpose is to allow network operations center (NOC) personnel to perform secure remote data center management and out-of-band management of IT assets from anywhere in the world. Products marketed as Console Servers usually 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. Marketing a product as a console server is very application specific because it really refers to what the user wants to do—remotely control, monitor, diagnose and troubleshoot equipment over a network or the Internet.Some users have created their own console servers using off-the-shelf commodity computer hardware, usually with multiport serial cards typically running a slimmed-down Unix-like
Unix-like
A Unix-like operating system is one that behaves in a manner similar to a Unix system, while not necessarily conforming to or being certified to any version of the Single UNIX Specification....
operating system such as Linux
Linux
Linux is a Unix-like computer operating system assembled under the model of free and open source software development and distribution. The defining component of any Linux system is the Linux kernel, an operating system kernel first released October 5, 1991 by Linus Torvalds...
. Such "home-grown" console servers can be less expensive, especially if built from components that have been retired in upgrades, and allow greater flexibility by putting full control of the software driving the device in the hands of the administrator. This includes full access to and configurability of a wide array of security protocols and encryption standards, making it possible to create a console server that is more secure. However, this solution may have a higher TCO
Total cost of ownership
Total cost of ownership is a financial estimate whose purpose is to help consumers and enterprise managers determine direct and indirect costs of a product or system...
, less reliability and higher rack-space requirements, since most industrial console servers have the physical dimension of one rack unit
Rack unit
A rack unit or U is a unit of measure used to describe the height of equipment intended for mounting in a 19-inch rack or a 23-inch rack...
(1U), whereas a desktop computer with full-size PCI
Peripheral Component Interconnect
Conventional PCI is a computer bus for attaching hardware devices in a computer...
cards requires at least 3Us, making the home-grown solution more costly in the case of a co-located
Colocation centre
A colocation centre or colocation center , is a type of data centre where equipment space and bandwidth are available for rental to retail customers...
infrastructure.
An alternative approach to a console server used in some cluster setups is to null-modem wire and daisy-chain consoles to otherwise unused serial ports on nodes with some other primary function.
External links
- Tom Fine: Console Server
- How to build your own console server using FreeBSDFreeBSDFreeBSD is a free Unix-like operating system descended from AT&T UNIX via BSD UNIX. Although for legal reasons FreeBSD cannot be called “UNIX”, as the direct descendant of BSD UNIX , FreeBSD’s internals and system APIs are UNIX-compliant...
- Remote Serial Console HOWTO
- Linux Serial Consoles for Servers and Clusters By Matthew Hoskins 2004
- Project Hydra: the USB Multiheaded Monster by Poul Petersen 2004