5.配置ssh免登陆
1）启动三台机器，分别修改机器名为master、slave1、slave2，重启系统。
[root@localhost ~]$ vim /etc/sysconfig/network #修改内容如下 NETWORKING = yes NETWORKING_IPV6 = no HOSTNAME = master #HOSTNAME为主机名，分别改一下就好。
2）修改master上的/etc/hosts。
#添加内容如下 192.168.222.131 master 192.168.222.132 slave1 192.168.222.133 slave2
3）将hosts文件复制到slave1和slave2。
[root@master ~]# scp /etc/hosts root@slave1:/etc
[root@master ~]# scp /etc/hosts root@slave2:/etc
4）在master机器上使用hadoop用户登录（确保接下来的操作都是通过hadoop用户执行）。执行￥ssh-keygen -t rsa命令产生公钥。
[hadoop@master ~]$ ssh-keygen -t rsa Generating public/private rsa key pair. Enter file in which to save the key (/home/hadoop/.ssh/id_rsa): Enter passphrase (empty for no passphrase): Enter same passphrase again: Your identification has been saved in /tmp/id_rsa. Your public key has been saved in /tmp/id_rsa.pub. The key fingerprint is: fa:2c:f7:98:9f:13:a1:7d:86:04:4c:54:5b:76:3e:01 hadoop@master The key‘s randomart image is: +--[ RSA 2048]----+ | +o.. E.o | | o + o . | | .. o | | o . | | S+ o | | .. + o | | . + | | .o.o.. | | o=o+. | +-----------------+
5）将公钥复制到slave1和slave2.
[hadoop@master tmp]$ ssh-copy-id -i ~/.ssh/id_rsa.pub slave1 #输入hadoop@slave1的密码 [hadoop@master tmp]$ ssh-copy-id -i ~/.ssh/id_rsa.pub slave2 #输入hadoop@slave2的密码
6）再次登录，已经可以不需要密码可以登录slave1，slave2.
[hadoop@master tmp]$ ssh slave1 Last login: Mon Jan 23 14:37:40 2017 from 192.168.0.112 [hadoop@slave1 ~]$
再后面是第六项安装Hadoop，配置文件我再研究研究。
【Hadoop大数据分析与挖掘实战】（二）----------P22~23
原文：http://www.cnblogs.com/Hootin-Pang/p/6362116.html