
Moderate
PuTTY is a client for running a remote session on a computer via the SSH, Telnet and Rlogin network protocols. In simple terms: you run PuTTY on a Windows machine, and tell it to connect to (for example) a Unix machine. PuTTY enables you to work on the Unix machine as if you were sitting at its console.
PuTTY is distributed under terms of the MIT license
Home Page An Introduction to SSH (secure shell) Connecting to a server via SSH.