Hadoop启动时SSH免密码登录

转自: https://blog.csdn.net/u011763190/article/details/50828410

现在在学习大数据，买了一台云服务器，照着网上的教程安装的。现在在启动（start-all.sh）Hadoop的时候老是要求输入密码，后面在真实环境下不可能每一次通信都要求手动输入密码的，所以，免密码很重要： 
现在直接上代码：

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:
a0:0d:8a:b4:dd:e7:92:6f:44:25:36:9a:5b:75:10:a8 root@richard
The key's randomart image is:
+--[ RSA 2048]----+
|        .oo      |
|       = o .     |
| .  . * = .      |
|..o..E +         |
|......=.S        |
|     .+.         |
|     o..         |
|      o.         |
|      ..         |
+-----------------+

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接下来将密钥写入ssh中

cat /root/.ssh/id_rsa.pub >> /root/.ssh/authorized_keys
/etc/init.d/ssh reload

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再次启动hadoop就没有密码输入的要求了。