PuTTY is a free software for programmers to help establish secure connections over the internet. Not only is it a useful encryption tool, it also is extremely reliable for connection based projects.
The popular remote shell client, PuTTY, is far more than a simple telnet connection tool. Originally produced for the Microsoft Windows platform, this free open source tool has been ported to a number of other platforms, with unofficial versions available for both Windows Mobile and Symbian. Official development is also in the works for a number of Linux/Unix environments as well as Mac OS. Overall though, significant use of PuTTY is somewhat limited to Microsoft Windows, which is why the developers of PuTTY make up for it by introducing a number of features that make it stand above other remote shell clients equally available.
PuTTY is able store your hosts using a function similar to Internet Browser History. This allows you to easily acces hosts you've connected to with your client box that you might not have saved for regular use.
PuTTY also recognizes your need for secure transmission. For this reason, PuTTY supports both SSH-1 and SSH-2 protocols, as well as public key authentication for SSH-2. RSA and DSA are both available for public key authentication, so it isn't a matter of being forced to employ one over the other. There are unofficial SSH alternatives, such as OpenSSH, and PuTTY does offer support for the later. Using PuTTYgen, you can turn your OpenSSH keys into the local PuTTY format.
When it comes to security, a powerful layer of security comes from local cryptographic efforts. PuTTY supports these with compatibility with a number of encryption techniques. With PuTTY, you will find complete support for DES, 3DES, AES, RC4 and Blowfish. Combined with noted SSH protocol, this results in a great deal of data security.
PuTTY also offers native forwarding for X11 protocol. This is a protocol for GUI communication between networked computers.
PuTTY even contains support for serial ports. These aren't particularly common, however certain businesses still use these to have their networked machines communicate with one another. As such, support provides backwards compatibility especially for older networks and machines with crucial data that has yet to be transferred to newer systems.
Different PuTTY files provide a great deal of functionality and each serve an important function for those that need to use them. The PuTTY file contains the client program from which users emulate a remote box via Telnet, among other protocols. PSCP is the PuTTY version of an SCP client allowing more secure file copy procedures. PSFTP is PuTTY's SFTP client which allows more secure FTP data to be downloaded as needed. PuTTYtel is the bare bones Telnet only client with absolutely no stress on security. Instead, the simple Telnet protocol with all of it's outdated flaws is usable. With PLink, you can gain command-line access to PuTTY operations. With Pageant, PuTTY performs it's routine SSH authentication as required by PuTTY, PSCP and PLink. PuTTYgen (mentioned above) can be used to generate not only DSA keys, but even RSA keys, for public key authentication. Finally, with pterm, you can emulate a terminal session with none of the added functionality.
PuTTY is not a significant download, as the entire product is contained in a single executable and requires none of the installation process with which you must already be quite familiar. It's also very resource efficient for a remote terminal client making it ideal for just about any situation that demands such a connection. Though it isn't as resource efficient as some other clients on the market, the margin by which it is more of a "hog" is so menial as to be meaningless on any modern computer. And with all the features for which PuTTY is known, this makes it the essential remote terminal client for Windows users.