ssh-keygen 产生公钥与私钥对
ssh-copy-id 将本机的公钥复制到远程机器的authorized_keys文件中，ssh-copy-id也能让你有到远程机器的home, ~./ssh , 和 ~/.ssh/authorized_keys的权利
假设，存在HostA和HostB两台Host，那么在HostA上可以执行下列命令进行无密码登录设置。
- 在HostA上创建公钥和密钥（一直按Enter）
[root@HostA]# ssh-keygen
Generating public/private rsa key pair.
Enter file in which to save the key (/home/jsmith/.ssh/id_rsa):[Enter key]
Enter passphrase (empty for no passphrase): [Press enter key]
Enter same passphrase again: [Pess enter key]
Your identification has been saved in /home/jsmith/.ssh/id_rsa.
Your public key has been saved in /home/jsmith/.ssh/id_rsa.pub.
The key fingerprint is:
33:b3:fe:af:95:95:18:11:31:d5:de:96:2f:f2:35:f9
- 用ssh-copy-id将公钥复制到远程机器中
[root@HostB]# ssh-copy-id root@HostB_IP