What is Putty and How Does It Work?

You have read or heard about Putty. But, you may wonder what Putty is and how it works. Well, we are going to explain it below. So, you have to make sure that you read it until the end so that you will get comprehensive information.

What Is Putty?

According to Wikipedia, Putty is a terminal emulator, serial console and network file transfer application which is free to use and open-source. It can support some network protocols such as SSH, SCP, Telnet, rlogin and raw socket connection. Also, it is able to connect to a serial port.

What is Putty and How Does It Work

Originally  Putty was written for Microsoft Windows. However, it has been ported to various other operating systems. The official ports are available for some Unix-like platforms, with work-in-progress ports to Classic Mac OS and macOS. The unofficial ports have been contributed to platforms such as Windows Mobile, Windows Phone and Symbian.

Putty has a number of features as you are able to see in the list below.

  • It has a Windows client. Also, Mac and Linux ports are available. There are no servers included.
  • It can support both 32-bit and 64-bit Windows. Since 2016, an MSI installer has been available.
  • It can support SSH client, telnet client, SFTP client and rlogin client. SSH2 and SSH1 protocols are also supported. It is important for you to know that the use of SSH1 is not recommended for security reasons. Practically, all devices can support SSH2 these days.
  • It can support public key authentication and active directory/ Kerberos authentication.
  • File transfers only use a separate command-line program. There is no integrated file transfer support.
  • It has no scripting support. However, it is able to be used together with WinSCP.

How Does Putty Works?

Usually, Putty is used on Windows. Even though it is also available on Linux. But, how does it work? Well, if you want to use it on your PC, you have to download it first. If you have downloaded it, you have to install it.

On Windows 10, the Edge browser offers to run the installer when the download is done. The thing that you have to do is to install the software. If you are using an older version of Windows, you will need to run the installer manually. You have to open the Windows Explorer and then you have to go to the Downloads directory. After that, you have to double click on the file name. It is important for you to know that the installation needs to be performed with administrator rights.

If the installer starts, it will show the welcome screen. The thing that you have to do is just click on Next. After that, the installer will ask for the Destination folder in which to install the software. It is better for you to use the default value. Then, you have to click on Next. The installer also will ask to choose product features to install. You may want to add a shortcut on the desktop if you want to use the software often. All the other options usually should be enabled. When it is ready, click on Install.

If the installation has done successfully, it will show a ‘Completed’ screen. You have to click on Finish now to exit the installer.

If the installation is done successfully, now the thing that you have to do is to test to make sure that Putty can run correctly and you are able to find the program. In case you installed a shortcut on the desktop, you must be able to find the icon for Putty. You are able to double click the icon. It will start the software.

Otherwise, you can find the software from the Windows Start menu in the bottom left corner of the screen. It is important for you to know that the menu looks different in each version of Windows. If you use Windows 10, you have to scroll down until you find Putty. Then, you have to open the group and then choose Putty.

When the software begins, there will be a window with the title ‘Putty Configuration’ with a field Host Name in the upper middle part. You have to try entering a host name to connect to in that field and then click on Open.

If you want to get a server, the first thing that you need to  know is that an SSH client is intended to be used for connecting to an SSH server. Because you have installed one, you have a server to connect. The server can be at your work, home or university. You will need a host name or IP address to connect to. Then, you have to enter the hostname or IP address in the Host Name.

In case you do not have a server but you want one, you are able to try to install Tectia SSH server for Windows for IBM mainframes or OpenSSH on Linux.

History and Maintenance Status

We can say that Putty is one of the oldest SSH clients for Windows. Firstly, it was released by Simon Tatham in 1998. In 2000, SSH support was added. Then, after 19 years, the software is still a beta version. The development of Putty seems slow. Nevertheless, it is still being maintained. A recent version added the support for elliptic curve cryptography. And in 15 years, if you pay attention to this, the user interface or features have not changed much.

In the Version 0.66 and earlier, it is known that it contains security vulnerabilities. It is recommended for you to upgrade to the latest version.

  • Buffer overflow in SCP which is a potential stack overflow and remote code execution vulnerability. If there is a corrupt server, it can execute code on the client when any file is downloaded. Also, it is able to be exploited by man in the middle attacks.
  • Integer overflow in terminal escape sequence handling which is a memory corruption and possible remote code execution vulnerability. It includes sending an escape sequence to the terminal.

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