useradd tom   # 添加用户

passwd tom    # 设置密码

vi /etc/ssh/sshd_config


# 修改内容
PermitRootLogin no      # 改成 no
Port 8222               # 改端口号

systemctl restart sshd

su - root

ssh-keygen

cat /root/.ssh/id_rsa.pub >> /root/.ssh/authorized_keys

vim /etc/ssh/sshd_config

# 禁止密码登陆
PasswordAuthentication no

systemctl restart sshd