putty ppk convert to OpenSSH key on MAC

First, open the puttygen.exe in windows.

you can download here => PuTTYgen

find the conversion toolbar item and select submenu export the ppk to the OpenSSH

ex.   foo_rsa



Then, put the foo_rsa file to /var/root/.ssh 


open terminal

#sudo cd /var/root/.ssh


#sudo chmod 600 foo_rsa


#ssh-add -K


#ssh username@yourhostname