全部生成公钥和私钥
将第1台的公钥拷到该目录特定文件authorized_keys中，
将第1台的authorized_keys scp到第2台机器，
将第2台的公钥拷到该目录特定文件authorized_keys中
将第2台的authorized_keys scp到第3台机器
将第3台的公钥拷到该目录特定文件authorized_keys中
将第3台的authorized_keys scp到第1台机器
所有集群机器
cd /root/
ssh-keygen -t rsa
#然后三个回车
[root@hadoop26 ~]# cat /root/.ssh/id_rsa.pub >> /root/.ssh/authorized_keys
此时authorized_keys只有hadoop26的公钥
[root@hadoop26 ~]# scp /root/.ssh/authorized_keys root@hadoop27:/root/.ssh/authorized_keys
[root@hadoop27 ~]# cat /root/.ssh/id_rsa.pub >> /root/.ssh/authorized_keys
此时authorized_keys有hadoop26,hadoop27的公钥
[root@hadoop27 ~]# cat /root/.ssh/authorized_keys
[root@hadoop27 ~]# scp /root/.ssh/authorized_keys root@hadoop28:/root/.ssh/authorized_keys
[root@hadoop28 ~]# cat /root/.ssh/id_rsa.pub >> /root/.ssh/authorized_keys
此时只有hadoop28的authorized_keys有hadoop26,hadoop27,hadoop28的公钥
[root@hadoop28 ~]# cat /root/.ssh/authorized_keys
[root@hadoop28 ~]# scp /root/.ssh/authorized_keys root@hadoop26:/root/.ssh/authorized_keys
此时hadoop26,hadoop28的authorized_keys有hadoop26,hadoop27,hadoop28的公钥
[root@hadoop28 ~]# scp /root/.ssh/authorized_keys root@hadoop27:/root/.ssh/authorized_keys
此时全部节点的authorized_keys有hadoop26,hadoop27,hadoop28的公钥
