Linux配置免密登录

多台服务器配置免密登陆

假设三台服务器192.168.1.111（node1）、192.168.1.112(node2)、192.168.1.113(node3)

比如hadoop用户下

groupadd hadoop      　　　　新建hadoop用户组

useradd -g hadoop hadoop 　 hadoop用户组下新建hadoop用户

passwd hadoop　　　　　　  修改hadoop用户的密码

hadoop用户的目录 /home/hadoop

切换到hadoop用户下

su hadoop

第一步：

　　每台服务器生成rsa公钥、私钥

　　ssh-keygen -t rsa

　　一路回车

　　id_rsa.pub即为公钥

[hadoop@node1 ~]$ ssh-keygen -t rsa
Generating public/private rsa key pair.
Enter file in which to save the key (/home/hadoop/.ssh/id_rsa): 
Created directory '/home/hadoop/.ssh'.
Enter passphrase (empty for no passphrase): 
Enter same passphrase again: 
Your identification has been saved in /home/hadoop/.ssh/id_rsa.
Your public key has been saved in /home/hadoop/.ssh/id_rsa.pub.
The key fingerprint is:
c7:c7:c5:fb:a5:5c:59:d6:eb:99:98:7b:31:9c:26:ae hadoop@node1
The key's randomart image is:
+--[ RSA 2048]----+
|                 |
|             .  .|
|              o +|
|         . . . o+|
|        S o o oo+|
|         . . o+X+|
|            .o=++|
|             ... |
|           E...  |
+-----------------+
[hadoop@node1 ~]$ 

第二步：

　　将每台服务器产生的公钥copy到第一台服务器192.168.1.111

　　ssh-copy-id hadoop@192.168.1.111

　　此时查看/home/hadoop/.ssh/authorized_keys

[hadoop@node1 .ssh]$ cat authorized_keys 
ssh-rsa AAAAB3NzaC1yc2EAAAADAQABAAABAQDMbR4B1rI+PqDfe/LqIOZyqNIoniayeKHzOC6gxqUFOEZXU15j8+qiJhd6ptgxpuLtlzpdypTZ3PjEHDKMKiNv9BOteo6Il9Q2x7gUCd2
dvbTbj0Sq4sJNasPS3twIu0h7pDvC2LqicF12mMNOTITAcHQo0b7urgJCQgoi7NlNYFWuJ/LzxqXWERTbMmCSzakm4X2foha+mY3ec0HfthMzzcJyrlyzrhTcSB19Lhw2uXWJWJPwL7R5Aa
r0qIIqjK/+084xMcTqucn4t3KFN/S1xIab60/QP/tNzMYF+Za0qg5xGgcRs1DxQPCTPEMghrUEaMgLFvxlpQOFrJAg9kOD hadoop@node1
ssh-rsa AAAAB3NzaC1yc2EAAAADAQABAAABAQC2Jn2Ozcqb+YacQzL8wdajfePXOuldqKBNc6byFMNWHU2AASl6RUlVw2vwilQ4SA0vwFZ2SLCQCOkdd4cKiGSCz+muro8/gTY9BomLw09
3sd3rkyLDDLfZ1CzmLemhuAgQ1vyxNBHTizVWaDlD7gSUuICpkHlXOVPqO/SS56sO/bGcDVe5cvyTL1Fy5L/ZKcyxPhmaLI4DzTfpBBgnSOSB81RNhzoEwRM8kudjnka4WtHBORn9HtM4E8
bnT9tPiGrpmEeo297LoerF3FCgmpxABA8mKmeLM/gOc+xzQkL008VjCN9oBcj2b+LH+E82jhbyHEv72ljRk/8S9bdJF1Vr hadoop@node2
ssh-rsa AAAAB3NzaC1yc2EAAAADAQABAAABAQDmB34n685esgquASpY31d4eq9zNgUmOXzW2F4RT3jHO1gOQiePqb5Kc6FA99IHyx28zfPJ/uKV+wek4Dk03jnQCmQAuVm6m4lxEBMiq83
OguGeqdfWbSAgqHeuXhy6+JHJzOY6xdtTvKwRDS3AGM3ewl4/4ZxLJDP8zY+4YptdvqDLA7ZYnoxxh7f680fpvvVtF073xopAGmDAe1u4/XXZvBCCZQCWMQlPuyRbmFh/uNSj8+yaKysNGe
/uAQ5xd2cpS7HAok+xv4D+w8xgr2KcSm9fD1+kH5M6/mpi2aLuhJCxJfW2KpbY+c8y19ObzgDzpxsw0vp4AL2Jzw6XcVrF hadoop@node3

第三步：

　　将192.168.1.111上的authorized_keys拷贝到另外两台服务器

　　scp /home/hadoop/.ssh/authorized_keys hadoop@192.168.1.112:/home/hadoop/.ssh/

　　scp /home/hadoop/.ssh/authorized_keys hadoop@192.168.1.113:/home/hadoop/.ssh/

第四步：

　　验证

　　192.168.111上

　　ssh hadoop@192.168.1.112

　　免密登陆成功。