RPM package
yum install putty
OS X: Install Homebrew
brew install putty
generate private key
puttygen id_dsa.ppk -O private-openssh -o id_dsa
public key
puttygen id_dsa.ppk -O public-openssh -o id_dsa.pub
Permission
mkdir -p ~/.ssh
mv -i ~/id_dsa* ~/.ssh
chmod 600 ~/.ssh/id_dsa
chmod 666 ~/.ssh/id_dsa.pub
chmod 666 ~/.ssh/known_hosts
Create public key by private key
ssh-keygen -f ~/.ssh/id_rsa -y > ~/.ssh/id_rsa.pub