Login SSH with .ppk

WHAT IS A .PPK FILE?
PPK files are PuTTY Private Key Files developed by Putty


convert .ppk file to .pem, copy it from Login SSH with .ppk file on Ubuntu Terminal

$ sudo apt-get install putty-tools

$ puttygen yourkey.ppk -O private-openssh -o yourkey.pem

$ ssh -i yourkey.pem serverusername@server-ip

ref:
1. WHAT IS A .PPK FILE?
2. Login SSH with .ppk file on Ubuntu Terminal