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A console server (also console access server or console management 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 32 or more, with varying features provided by their embedded software.

Many users have created their own console servers using off-the-shelf commodity computer hardware, usually with multiport serial cards (such as those from Cyclades or Digi), 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 an higher TCO, less reliability and higher rack-space requirements, because most industrial console servers are 1U and 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.

One of the biggest concerns with console servers is that of security. Typically the devices a console server allows you to connect with has one common login and one common password. Therefore tracing back to the identity of who made what change when is almost impossible. Everyone that gets access to the console server can access everything. Companies will need to deploy role based security that is already available in their RADIUS or TACACS servers.

As security and compliance audits continue to close the loop, console servers will be subjected to scrutiny on console server access and permissions requiring to adhere to the corporate security standards. Requiring individual logins, logging all commands and the resulting output for each command, all stored historically for auditing.

Major suppliers of console servers (in alphabetical order) includes:

• Avocent (including Cyclades)
• Cisco
• Digi International
• Lantronix
• Opengear
• Perle
• Raritan
• Tibbo
• Uplogix

• Conserver
• Terminal server
• KVM Switch

• Tom Fine: Console Server
• Zinc is a console log output management program
• Dr Richard Bemrose: Console Management and Security 2004 Cambridge Online
• How to build your own console server using FreeBSD
• 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
• Ser2net Serial port to network proxy
• UNIX Serial Port Resources including console and terminal server information and port/cable pinouts