1. 创建ssh-key
这里我们采用rsa方式，使用如下命令：
xiaosi@xiaosi:~$ ssh-keygen -t rsa -f ~/.ssh/id_rsa
Generating public/private rsa key pair.
Created directory '/home/xiaosi/.ssh'.
Enter passphrase (empty for no passphrase):
Enter same passphrase again:
Your identification has been saved in /home/xiaosi/.ssh/id_rsa
