Telnet is now made an optional component in Vista and Longhorn Servers. This means if you type telnet in command shell, you will be out of luck.

Why have we done it so?

As time has passed, fewer users use telnet. Thus, to decrease the foot print as well as the attack surface, we decided to make it an optional component.

Great, now how do I get telnet client/server working again?

Vista -

Use software explorer or Click Start, Control Panel, Programs, and then Turn Windows Features on or off. In the list, scroll down and select Telnet Client. Click OK to start the installation.

Longhorn -

Use RMT to install

If you want to use command line options - please use the following commands -

Command line to install telnet server:

start /w pkgmgr /iu:"TelnetServer"

Command line to install telnet server:

start /w pkgmgr /iu:"TelnetClient"

So have a try and let me know!