Telnet is an Internet-standard utility and protocol based on Request for Comments (RFC) 854. This RFC specifies a method for transmitting and receiving unencrypted ASCII characters (plaintext) across a network. You can use a Telnet client running on one computer to connect to a command line-based session to run applications. Only character-based interfaces and applications are supported. There is no graphics capability in the Telnet environment.
The RFC documents that define Telnet can be found at the Internet Engineering Task Force Web site (http://go.microsoft.com/fwlink/?linkid=121). On that page, click RFC Pages, and then type 854 in the RFC number text box and click Go.
Telnet consists of two components: Telnet Client and Telnet Server.
Telnet Server hosts the remote sessions for Telnet clients. When Telnet Server is running on a computer, users can connect to the server with a Telnet client from a remote computer. Telnet Server is implemented in Windows as a service that can be configured to always run, even when no one is logged on to the server.
When a Telnet client connects to a computer running Telnet Server, the remote user is asked to enter a user name and password. The user name and password combination must be one that is valid on the Telnet Server. Telnet Server on Windows supports two types of authentication: NTLM and Password (or plaintext).
Once logged on, a user is presented with a command prompt that can be used as if it had been started locally on the server console. Commands that you type at the Telnet client command prompt are sent to the Telnet Server and executed there, as though you were locally logged on to a command prompt session at the server. Output from the commands you run are sent back to the Telnet client where they are displayed for you to view.
Telnet does not support applications that require a graphical user interface. However, Telnet Server and Telnet Client understand special character sequences that provide some level of formatting and cursor positioning within the Telnet client window. Telnet Server and Telnet Client support the emulation of four types of terminals: ANSI, VT-100, VT-52, and VT-NT.
Installing Telnet Server
On Windows Server 2008, you can install Telnet Server by using the Add Features Wizard in Server Manager. Although Server Manager opens by default when a member of the Administrators group logs on to the computer, you can also open Server Manager by using commands on the Start menu in Administrative Tools, and by opening Programs in Control Panel. On Windows Vista and later versions, you can install Telnet Server (and Telnet client) by opening Control Panel, then Programs, and then Turn Windows features on or off.
For more information about installing or using Telnet Server, see the Telnet Operations Guide (http://go.microsoft.com/fwlink/?linkid=86992) on the Microsoft Web site.