免密传输文件方法:
1. 设备上制作密钥: ssh-keygen -t rsa
Generating public/private rsa key pair.
Enter file in which to save the key (/root/.ssh/ssh/id_rsa): #回车
Enter passphrase (empty for no passphrase): #回车
Enter same passphrase again: #回车
Your identification has been saved in /root/.ssh/id_rsa.
Your public key has been saved in /root/.ssh/id_rsa.pub.