（五）hadoop系列之__集羣搭建SSH無密訪問多臺機器

免密碼ssh設置
如今確認可否不輸入口令就用ssh登陸localhost: $ ssh localhost
若是不輸入口令就沒法用ssh登錄localhost，執行下面的命令：

1. 並修改hosts映射:
  
  添加：(配置三臺機器hosts,保證能夠互相訪問)
  $ vi /etc/hosts
    127.0.0.1       localhost.localdomain   localhost
    192.168.126.10  master.localdomain master
    192.168.126.20  slave1.localdomain slave1
    192.168.126.30  slave2.localdomain slave2
2. 生成三臺機器的密鑰和公鑰 
    $  ssh-keygen  -t rsa -f ~/.ssh/id_rsa #生成祕鑰和公鑰
    $ cat ~.ssh/id_rsa.pub >> ~/.ssh/authorized_keys //把當前主機的公鑰添加到authorized_keys文件

    $ scp .ssh/id_rsa.pub root@192.168.126.10:/home/hadoop/.ssh/authorized_keys_slave1 //複製slave1公鑰添加到authorized_keys_slave1文件
    $ scp .ssh/id_rsa.pub root@192.168.126.10:/home/hadoop/.ssh/authorized_keys_slave2 //複製slave2公鑰添加到authorized_keys_slave2文件


3.把slave1和slave2的公鑰追加到authorized_keys
    $ cat /home/hadoop/.ssh/authorized_keys_slave1 >> /home/hadoop/.ssh/authorized_keys
    $ cat /home/hadoop/.ssh/authorized_keys_slave2 >> /home/hadoop/.ssh/authorized_keys
     master配置
     ################master#################
    $ cat id_rsa.pub >> authorized_keys
    $ cat authorized_keys_slave1 >> authorized_keys
    $ cat authorized_keys_slave2 >> authorized_keys
    $ chmod 644 authorized_keys//修改權限 
     ######################################                        
                        
4.把主機的公共密鑰複製到slave1和slvae2
    $ scp id_rsa.pub root@192.168.126.20:/home/hadoop/.ssh/authorized_keys_master
    $ scp id_rsa.pub root@192.168.126.30:/home/hadoop/.ssh/authorized_keys_master
    slave1配置
    ##################slave1#####################
    cat id_rsa.pub >> authorized_keys
    cat authorized_keys_master >> authorized_keys
    chmod 644 authorized_keys
    ######################################    
    slave2配置
    ##################slave2#####################
    cat id_rsa.pub >> authorized_keys
    cat authorized_keys_master >> authorized_keys
    chmod 644 authorized_keys
  #######################################

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最後測試：

master主機訪問slave1和slave2:

ssh 192.168.126.20 //回車，若是切換到slave1,則訪問成功。slave3同理。