前言

请确保三台主机可以互相Ping通
尽量去做”快照“备份，以免发生故障后及时恢复，避免造成更大的损失。
本次使用软件：Xshell 6：蓝奏下载，百度网盘下载Xshell6 - 提取码: x2f3
Xshell使用技巧请参阅：Hadoop集群搭建-Xshell小技巧-基于CentOS7-【连载中】

正文

配置hosts文件

Xshell连接三台主机，步骤详见：5.2 Hadoop集群搭建-Xshell新建会话连接图解-基于CentOS7-【连载中】
将三台主机页面设置为”瓷砖排列“，详见：Hadoop集群搭建-Xshell小技巧-基于CentOS7-【连载中】
在Master窗口输入vim /etc/hosts（需要提前安装vim彩色代码命令：yum install -y vim）
在最后一行输入IP地址空格后输入主机名，每个主机IP和主机名后要回车，也就是每个主机各占一行
保存后发送到其他两台主机（需要输入其他两台主机的密码，需要输入”yes“时请输入”yes“）：scp /etc/hosts root@slave1:/etc/

[root@localhost ~]# scp /etc/hosts root@slave1:/etc/
The authenticity of host 'slave1 (192.168.***.***)' can't be established.
ECDSA key fingerprint is SHA256:1uOH6LWY9vqqbkbz93f6fbsHV/jKPEN8I0Zm37qb1ZU.
ECDSA key fingerprint is MD5:05:d2:b6:50:5f:32:f1:38:92:d9:c2:8e:df:42:e6:dc.
Are you sure you want to continue connecting (yes/no)? yes
Warning: Permanently added 'slave1,192.168.**.***' (ECDSA) to the list of known hosts.
root@slave1's password: 
hosts                                                                                       100%  224   217.8KB/s   00:00    
[root@localhost ~]# scp /etc/hosts root@slave2:/etc/
The authenticity of host 'slave2 (192.168.**.***)' can't be established.
ECDSA key fingerprint is SHA256:1uOH6LWY9vqqbkbz93f6fbsHV/jKPEN8I0Zm37qb1ZU.
ECDSA key fingerprint is MD5:05:d2:b6:50:5f:32:f1:38:92:d9:c2:8e:df:42:e6:dc.
Are you sure you want to continue connecting (yes/no)? yes
Warning: Permanently added 'slave2,192.168.***.****' (ECDSA) to the list of known hosts.
root@slave2's password: 
hosts                                                                                       100%  224   154.8KB/s   00:00

配置免密

三台主机都要输入：ssh-keygen -t rsa生成密钥
- 解释：


Enter file in which to save the key (/root/.ssh/id_rsa):(/root/.ssh/id_rsa)
密钥的生成路径保存的位置为(/root/.ssh/id_rsa)，如果默认即回车，不默认即在冒号后方输入自己的路径
/root/.ssh/id_rsa already exists.
Overwrite (y/n)?出现这个是因为之前配置过（生成过）密钥，询问是否覆盖，y是覆盖，n是不覆盖。
Enter passphrase (empty for no passphrase):输入密钥的密码，不需要直接回车
Enter same passphrase again:再次输入相同的密码（和上一步一样，跳过。如果上一步输入了密码这一步就要输入同样的密码。）
回车密钥生成

在撰写栏中一路回车（建议参阅5.1 Hadoop集群搭建-Xshell小技巧-基于CentOS7-【连载中】后使用更流畅）：
撰写栏输入（也就是三台主机都要输入）ssh-copy-id master将密钥发送给master主机：

[root@localhost ~]# ssh-copy-id master
/usr/bin/ssh-copy-id: INFO: Source of key(s) to be installed: "/root/.ssh/id_rsa.pub"
The authenticity of host 'master (192.168.**.***)' can't be established.
ECDSA key fingerprint is SHA256:1uOH6LWY9vqqbkbz93f6fbsHV/jKPEN8I0Zm37qb1ZU.
ECDSA key fingerprint is MD5:05:d2:b6:50:5f:32:f1:38:92:d9:c2:8e:df:42:e6:dc.
Are you sure you want to continue connecting (yes/no)? yes
/usr/bin/ssh-copy-id: INFO: attempting to log in with the new key(s), to filter out any that are already installed
/usr/bin/ssh-copy-id: INFO: 1 key(s) remain to be installed -- if you are prompted now it is to install the new keys
root@master's password: 

Number of key(s) added: 1

Now try logging into the machine, with:   "ssh 'master'"
and check to make sure that only the key(s) you wanted were added.

转到master输入：cd /root/.ssh/使用ls查看该目录下文件：

[root@localhost ~]# cd /root/.ssh/
[root@localhost .ssh]# ls
authorized_keys  id_rsa  id_rsa.pub  known_hosts

将authorized_keys文件发送到其他两台从机：scp authorized_keys root@slave1:/root/.ssh/

[root@localhost .ssh]# scp authorized_keys root@slave1:/root/.ssh/
root@slave1's password: 
authorized_keys                                                                             100% 1224     1.0MB/s   00:00    
[root@localhost .ssh]# scp authorized_keys root@slave2:/root/.ssh/
root@slave2's password: 
authorized_keys                                                                             100% 1224     1.1MB/s   00:00