/etc/ssh/sshd_config

RSAAuthentication yes        # 啟用 RSA 認證，默認為yes
PubkeyAuthentication yes     # 啟用公鑰認證，默認為yes

generate client public and private key

 ssh-keygen -t rsa

Step 3

cat id_rsa.pub >> .ssh/authorized_keys

prevent user from login by password

/etc/sshd/sshd_config

PasswordAuthentication no
 

modify mode

chmod 700 ~/.ssh
chmod 600 ~/.ssh/authorized_keys

ssh public key to login server