[xiao@xiao .ssh]# ssh-keygen -t rsa
Generating public/private rsa key pair.
Enter file in which to save the key (/home/xiao/.ssh/id_rsa):
Enter passphrase (empty for no passphrase):
Enter same passphrase again:
Your identification has been saved in /home/xiao/.ssh/id_rsa.
Your public key has been saved in /home/xiao/.ssh/id_rsa.pub.
The key fingerprint is:
b7:90:79:46:cb:1d:3b:a5:56:2d:09:95:e4:f2:b7:4a xiao@xiao

如果不需要密码的自动登录，在这里就不需要输入任何东西。
将生成的/home/xiao/.ssh/id_rsa.pub的内容复制到远程帐户目录下，具体是
~account/.ssh/authorized_keys，要保证authorized_keys的权限是700。

这样就可以ssh自动登录远程帐户了。