环境

VMware版本号：12.0.0

CentOS版本：CentOS 7.3.1611

三台虚拟机(IP)：

192.168.252.121
192.168.252.122
192.168.252.123

1.修改主机名

修改三台主机名，以此类推，node1，node3，node3

命令格式
hostnamectl set-hostname <hostname>


$ hostnamectl set-hostname node1

剩下的虚拟机依次修改hostnamectl set-hostname[1-3]

重启操作系统

$ reboot

2.修改映射关系

1.在 node1 的 /etc/hosts 文件下添加如下内容

$ vi /etc/hosts

2.查看修改后的/etc/hosts 文件内容

$ cat /etc/hosts
127.0.0.1   localhost localhost.localdomain localhost4 localhost4.localdomain4
::1         localhost localhost.localdomain localhost6 localhost6.localdomain6
# 以下是添加的
192.168.252.121 node1
192.168.252.122 node2
192.168.252.123 node3

2.将集群node1 上的文件hosts文件 通过 scp 命令复制发送到集群的每一个节点

$ for a in {1..3} ; do scp /etc/hosts node$a:/etc/hosts ; done

3.检查是否集群每一个节点的 hosts 文件都已经修改过来了

$ for a in {1..3} ; do ssh node$a cat /etc/hosts ; done

3.启动 ssh 无密登录

1.在集群node1的 /etc/ssh/sshd_config 文件去掉以下选项的注释

$ vi /etc/ssh/sshd_config 

RSAAuthentication yes      #开启私钥验证
PubkeyAuthentication yes   #开启公钥验证

2.将集群node1 修改后的 /etc/ssh/sshd_config 通过 scp 命令复制发送到集群的每一个节点

$ for a in {1..3} ; do scp /etc/ssh/sshd_config node$a:/etc/ssh/sshd_config ; done

4.生成公钥、私钥

1.在集群的每一个节点节点输入命令 ssh-keygen -t rsa -P ”，生成 key，一律回车

$ ssh-keygen -t rsa -P ''

[root@node1 ~]# ssh-keygen -t rsa -P ''
Generating public/private rsa key pair.
Enter file in which to save the key (/root/.ssh/id_rsa): 
Your identification has been saved in /root/.ssh/id_rsa.
Your public key has been saved in /root/.ssh/id_rsa.pub.
The key fingerprint is:
22:42:2d:15:39:cc:f6:4a:9c:da:57:5b:55:b8:18:5d root@node1
The key's randomart image is:
+--[ RSA 2048]----+
|   ooo     . +E  |
|   o*     . +    |
|  oo.+     + .   |
| . .+ . . o .    |
|  .+....So       |
|  ..o....        |
|     .           |
|                 |
|                 |
+-----------------+

2.在集群的node1 节点输入命令

将集群每一个节点的公钥id_rsa.pub放入到自己的认证文件中authorized_keys;

for a in {1..3}; do ssh node$a cat /root/.ssh/id_rsa.pub >> /root/.ssh/authorized_keys; done

3.在集群的node1 节点输入命令

将自己的认证文件 authorized_keys 通过 scp 命令复制发送到每一个节点上去: /root/.ssh/authorized_keys`

for a in {1..3}; do scp /root/.ssh/authorized_keys node$a:/root/.ssh/authorized_keys ; done

4.清除node1 节点下的 .ssh/known_hosts 文件

rm -rf ~/.ssh/known_hosts

5.在集群的每一个节点节点输入命令重启ssh服务

systemctl restart sshd.service

5.验证 ssh 无密登录

开一个其他窗口测试下能否免密登陆

例如：在node3

[root@node3 ~]# ssh node1
The authenticity of host 'node1 (192.168.252.121)' can't be established.
ECDSA key fingerprint is ab:0f:08:20:3d:7a:11:05:ea:d9:b0:0c:9e:e1:d0:97.
Are you sure you want to continue connecting (yes/no)? yes
Warning: Permanently added 'node1,192.168.252.121' (ECDSA) to the list of known hosts.
Last login: Tue Aug 22 14:00:18 2017 from 192.168.252.1

exit 退出

[root@node1 ~]# exit
logout
Connection to node1 closed.

注意：开新的其他窗口测试下能否免密登陆，把当前窗口都关了