So far, we've looked at clients that allow you to transfer information to and from servers on the Internet. Sometimes though, you need to actually use the computer your connecting to, whether to run a program, search a database, or modify a file directly. In this case, you need to log into the computer using an application called telnet. This connects to a remote computer and allows you to use it just as if you were sitting at its keyboard.

Like a web browser, telnet is a client application that connects to a server. But unlike the web, telnet allows you to interact directly with the command-line interface of the server computer. It's also synchronous, which means that it's often used to connect to real-time servers such as virtual worlds or chat programs.

Terminal Emulation. When you connect to a server using telnet, you are emulating a terminal connected physically to that computer. As there are many types of terminal, you need to choose which type you want to be to access the server--this is called the terminal emulation. Normally, you can select this in the telnet client's preferences. Often, wierd things happen if you select the wrong terminal type, so if you get random characters splurged all over the screen, try a different emulation. The most common setting is called vt100, so it's worth trying that one first.

Secure versions of Telnet. As with FTP, telnet is not a very secure way of connecting to a computer. If you need to connect to a remote computer regularly, or need to access sensitive information or use administrator privileges, then you need to use a secure version of Telnet, such as SSH. This protocol is widely available in many products; my preference is for PuTTY which is very reliable and is free.