PuTTY is a free and very popular program implementing Telnet, SSH and Rlogin client services, operating under Microsoft Windows and Unix/Linux operating systems. It is a fully configurable client both in the sphere of protocols and user interface: it takes into account different terminal properties (different line end codes, monochromatic display, echo, etc.), allows you to change the color scheme used, full configuration of the window (size, fonts, keyboard type), operation of tunnels, preservation of session settings.

The program works very well with Linux. It implements AES, 3DES, Blowfish and DES encryption. In addition to the client itself, a number of applications supporting communication and authentication based on secure, key-based protocols are available.