A console server (or serial 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 ports, 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.
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.