Telnet Installation Across Linux and Windows

Linux

If you're certain you understand the security implications, read on. Otherwise, you might be better off looking in to an ssh server.

Most unix like operating systems make a telnet server/daemon available. Check the man pages and your operating system documentation for more details. Below are a couple of examples for installing telnetd:

• Ubuntu: [root@host ~]$ apt-get install telnetd
• CentOS / Redhat / Fedora: [root@host ~]$ yum install telnetd

WIndows:

If you're certain you understand the security implications, read on. Otherwise, you might be better off looking in to the various Windows remote access options and services.

Microsoft makes this knowledge base document available for installing and enabling the telnet service on Windows. It covers a variety of Windows versions: 
http://technet.microsoft.com/en-us/library/cc770501(v=ws.10).aspx