免密登陆

一、准备工作

1) 用客户端工具（ssh client或者putty）连接到linux服务器。在root用户下输入命令

vi /etc/hosts,用vi编辑hosts文件，如下：
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#127.0.0.1   localhost localhost.localdomain localhost4 localhost4.localdomain4

#::1         localhost localhost.localdomain localhost6 localhost6.localdomain6

192.168.1.160 hadoop01

192.168.1.161 hadoop02

192.168.1.162 hadoop03

192.168.1.163 hadoop04

192.168.1.164 hadoop05

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2) 输入命令：cd .ssh进入rsa公钥私钥文件存放的目录，删除目录下的id_rsa，id_rsa.pub文件。
二、在每台机上产生新的rsa公钥私钥文件，并统一拷贝到一个authorized_keys文件中

1) 登录hadoop01，在.ssh目录下输入命令：

ssh-keygen -t rsa

，三次回车后，该目录下将会产生id_rsa，id_rsa.pub文件。其他主机也使用该方式产生密钥文件。

2) 登录hadoop01，输入命令：

cat id_rsa.pub >> authorized_keys

,将id_rsa.pub公钥内容拷贝到authorized_keys文件中。

3) 登录其他主机，将其他主机的公钥文件内容都拷贝到hadoop01主机上的authorized_keys文件中，命令如下：
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ssh-copy-id -i hadoop01 #登录hadoop02,将公钥拷贝到hadoop01的authorized_keys中

ssh-copy-id -i hadoop01#登录hadoop03,将公钥拷贝到hadoop01的authorized_keys中

ssh-copy-id -i hadoop01#登录hadoop04,将公钥拷贝到hadoop01的authorized_keys中

ssh-copy-id -i hadoop01 #登录hadoop05,将公钥拷贝到hadoop01的authorized_keys中，最终authorized_keys文件内容如下：

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[root@hadoop01 .ssh]# more authorized_keys

ssh-rsa AAAAB3NzaC1yc2EAAAABIwAAAQEAp7jp4a1/deK4B/eZW8kdiCQvzpKe4Id0uP0DdONFW85r

20rpH4ZpNSB7JNYFiqjMUPQ/2EWLXh7xoa9UntKsMVVcZr3BTiXRZ0Gx7IDacwz8Cq0qYrwUCMTKt7QF

xK5RwXyuZqDFjc2yC3/ZoqeyeLERFTll3ZLGeFsXhJjlkPTvtnvx0zX6lacPZL4VguoM5YHw3KaJg8bd

qehJzbQoPS8sm00ES4iygbR+Ixz1cnGTrtNU1S3lh4/y0PC6spMs9Z2Mf097FTLQJXJDiGqU9Tq3MHvl

srZFx92H4yeiJuYWJaZImuiq/feRIo30Dig6obEfuAn13vevdXozcXNlYQ== root@hadoop03

ssh-rsa AAAAB3NzaC1yc2EAAAABIwAAAQEAwpEgmBzfGw1mrKy3Ho8k/h4jrZlRdIzuLs6PKqDPV/Cw

2kjSYXV7tyGklUYWPWr1Dt6kw5+Ojr7zv+cFnFWKzTTAJz3V4md0RyQ11Kb+IJA7b88SRHcVLlNF2GDX

N2pVqh9lf6Zu6zfpnAjCg/mU8qzTrZfFZdzPtBppimMq+l0bolvgnxEEkpFTNkpHB8+cD732WL+KiW52

7nt0LGBbVbZz9mUa+0bsPGK7ySfk1SPUkGyNXXqVjEydyjvRY8bob7Q3mFX3MpDT696R8n7U7hQ7u4b8

gbe3rIuQcWwGseEQrGjIDhLb9am3dbgDuFeg73RJqFZMOp2y6zQF3jQIew== root@hadoop02

ssh-rsa AAAAB3NzaC1yc2EAAAABIwAAAQEAmc2M6Bzw1cPaDwjbtgynJPWRKv9pDnHjBSn5BDbIX0po

8GHHGr1pvYMGu4XWlIa76O44+bmF32K/9ECzBcNVL6a+aN5HWdUPpE6zagFUcaewXu2p4+FCZWpoTZbj

zHKGeay35Id+mpltZUWZlR5lOX+G/veNzuZNpKXnVYoZdAaJ3XlH6IVhKlGOuZkXxvD7e+YD4oxZw+4o

iaav/QtAhZHXWcAt2eVj9xw+j/3Ip5ImmIWHv5/AOFrgiY6c6U+2g5xOGONINbh9CxQ1L4HbQVAx8hYC

stWUm0LfFAcMwXDwb8RAFj+cH+D/xG6CrORLb4UfroJHa6N64rx/5dmz7w== root@hadoop04

ssh-rsa AAAAB3NzaC1yc2EAAAABIwAAAQEAxAsHr8Jp4vXI7bPGmSsO/+bT43GsxQ4GKdGf8qLPsFY+

/KluWl0TrRLwBVHGc94gpN2JOqtvKYYDSHw4Fj6KPSk/6Nt8CutZAwASoVxzexTFMOSwNFpTMsLc7Oza

Q3XG6v6PgtBEJqdUdl4zIFAZnkZjKmZp8SWG1jGo/vl3jsbrnmFQFeH04MdVcm9r1wvl80bdF9YvYEtg

ymHO4/tANKWSNKGw2EcthNWyQiN4hIYOoBQaUA3FlAXyqcD2+Q+2frf0gNF5KfKKLXmmlAuS9Oi6JqFJ

f1BLmMquI4n02owzU0zlkj3Px5IcCfQbDQ/JedHcjxEKP2S+9m3yxG4h2Q== root@hadoop05

ssh-rsa AAAAB3NzaC1yc2EAAAABIwAAAQEAyS1PbXTgFqHcGV/k0QUZni5xB5+q71qx4r5xto+WLkVQ

MiS3gR/VYZoyDLrQRVf5t0JiliCgHeU0MG/ASd1LPbsVYCX5V9cmcm1hMByDKJ6FwIxz5cY4y1dBpwAZ

2E24CQWfZuevaeIFnL80RGGLhRgCxbLb3aPvRZuV34utD+5kgAFJwYCQYN4KnFG1S5e4X6U5J3FsCDby

GD7dhtWWktMV2SAnWjrmULguaVRqO0sDIEiVSc9+KKqAmlOab+5SbZAI5+3hzJog5c3i4f5fHXWnxYqy

LNo3yYSWraV5KcYIlNPqX6iJKvjLWbNDwD3+70u4nWjBSXXufhff71LdHw== root@hadoop01

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三、授权authorized_keys文件

1) 登录hadoop01,在.ssh目录下输入命令：

chmod 600 authorized_keys

,效果如下：
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[root@hadoop01 .ssh]# ls -al

total 28

drwx------.  2 root root 4096 Oct 24 12:27 .

dr-xr-x---. 22 root root 4096 Oct 24 19:20 ..

-rw-------.  1 root root 1975 Oct 24 12:27 authorized_keys

-rw-------.  1 root root 1975 Oct 24 12:09 authorized_keys_20141024

-rw-------.  1 root root 1675 Oct 24 12:23 id_rsa

-rw-r--r--.  1 root root  395 Oct 24 12:23 id_rsa.pub

-rw-r--r--.  1 root root 2020 Oct 24 12:10 known_hosts

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四、将授权文件分配到其他主机上

1) 登录hadoop01,将授权文件拷贝到hadoop02、hadoop03...,命令如下：
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scp /root/.ssh/authorized_keys hadoop02:/root/.ssh/ #拷贝到hadoop02上

scp /root/.ssh/authorized_keys hadoop03:/root/.ssh/ #拷贝到hadoop03上

scp /root/.ssh/authorized_keys hadoop04:/root/.ssh/ #拷贝到hadoop04上

scp /root/.ssh/authorized_keys hadoop05:/root/.ssh/ #拷贝到hadoop05上

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2) 至此，免密码登录已经设定完成，注意第一次ssh登录时需要输入密码，再次访问时即可免密码登录。

转载于:https://www.cnblogs.com/QAZLIU/p/8998300.html