1.生成公钥和私钥：
[pw@hadoop010 ~]$ ssh-keygen -t rsa
然后敲（三个回车），就会生成两个文件id_rsa（私钥）、id_rsa.pub（公钥
2.将公钥拷贝到要免密登录的目标机器上
[pw@hadoop010 .ssh]$ ssh-copy-id hadoop010
[pw@hadoop010 .ssh]$ ssh-copy-id hadoop011
[pw@hadoop010 .ssh]$ ssh-copy-id hadoop012
3..ssh文件夹下（~/.ssh）的文件功能解释
| known_hosts | 记录ssh访问过计算机的公钥(public key) |
|---|---|
| id_rsa | 生成的私钥 |
| id_rsa.pub | 生成的公钥 |
| authorized_keys | 存放授权过得无密登录服务器公钥 |