PEM is a container format that could among other things be used to store certificate authority (CA) files, SSH public and private keys or Root SSL certificate.
You will not be able to directly use a .pem SSH private key using programs like PuTTY as PuTTY only accept .ppk (PuTTY Private Key) files. For this you'll have to convert a .pem file to .ppk using PuTTY Key Generator or PuTTYGen.
Steps to convert pem file to ppk using PuTTYGen:
Download
PuTTY Key Generator (
puttygen.exe) from the official website and launch the program.

https://www.chiark.greenend.org.uk/~sgtatham/putty/latest.html
Click on the
Load button from
PuTTYgen's main interface.

Set the
Files of type to
All Files (*.*), select your
PEM file and click
Open.

Enter the passphrase of your
PEM private key file if prompted and click
OK.

Click
OK on the successful import of the file notification.

Edit any key parameters if necessary and click
Save private key.

Click
Yes if you don't set any passphrase on your key before and getting warned about it.

Select the location and filename to save the generated key to and click
Save.

Author:
Mohd Shakir Zakaria Cloud architect by profession but always consider himself as a developer, entrepreneur and an opensource enthusiast.
Discuss the article:
Comment anonymously. Login not required.