Mastering SSH: How to Convert Your PEM Keys to PuTTY’s PPK Format (Linux and Windows)

Introduction

SSH keys come in different formats, with PEM (Privacy Enhanced Mail) and PPK (PuTTY Private Key) being two common ones. Different SSH clients and servers expect keys in specific formats. For instance, PEM is commonly used with OpenSSH on Unix systems, while PPK is the format for PuTTY, a popular SSH client on Windows. Converting between these formats ensures compatibility and seamless connectivity across different platforms. The following guide will show you how easy it is to do this conversion.

Easy: Converting Using PuTTYgen on Windows

1. Download and Install PuTTYgen: Get the latest version of PuTTYgen from puttygen.com and install it. This tool is part of the PuTTY suite which is essential for SSH communications on Windows​​.

2. Load the PEM File: Open PuTTYgen, and click the ‘Load’ button. Change the file type to *.* to locate your PEM file​​.

3. Convert and Save: Once the PEM file is loaded, simply click ‘Save Private Key’. PuTTYgen will then convert the PEM file to PPK format​​.

Medium Skill: Converting Using PuTTY Tools on RHEL Compliant Systems (RHEL, CentOS, Rocky, Alma etc)

1. Install PuTTY Tools: On a Red Hat Enterprise Linux (RHEL) system, you can install PuTTY tools using a package manager. For example, using the command:

sudo yum install putty

On Debian based systems such as Ubuntu

sudo apt-get install putty-tools

2. Convert Using Command Line: Use the puttygen command to convert the PEM file. For example:

puttygen id_rsa.pem -O private -o id_rsa_private.ppk 

This command converts id_rsa.pem to a PPK file named id_rsa_private.ppk​​.

Conclusion

This guide provides a straightforward process for converting SSH keys between PEM and PPK formats using PuTTYgen on Windows and PuTTY tools on RHEL and Ubuntu-based Linux systems. Understanding these methods is crucial for ensuring compatibility across different SSH clients and platforms.