导读 linux系统中密码的保存是非常重要的,在企业中的WEB集群环境中,进行统一的版本更新和配置文件的同步免密登录是非常重要的。在自动化运维,统一管理都是离不开Linux的免密登录。下面我们来看下免密登录。
1.Linux下生成密钥

ssh-keygen的命令手册,通过”man ssh-keygen“命令:

通过命令”ssh-keygen -t rsa“

生成之后会在用户的根目录生成一个 “.ssh”的文件夹

进入“.ssh”会生成以下几个文件

authorized_keys:存放远程免密登录的公钥,主要通过这个文件记录多台机器的公钥

id_rsa : 生成的私钥文件

id_rsa.pub : 生成的公钥文件

know_hosts : 已知的主机公钥清单

如果希望ssh公钥生效需满足至少下面两个条件:

1) .ssh目录的权限必须是700 2) .ssh/authorized_keys文件权限必须是600

2.远程免密登录

原理图:

常用以下几种方法:

2.1 通过ssh-copy-id的方式

命令: ssh-copy-id -i ~/.ssh/id_rsa.put

举例:

[root@test .ssh]# ssh-copy-id -i ~/.ssh/id_rsa.pub 192.168.91.135
root@192.168.91.135's   password:
Now try logging into the machine, with "ssh '192.168.91.135'", and check in:
.ssh/authorized_keys  to make sure we haven't added extra keys that you weren't expecting.
[root@test .ssh]# ssh root@192.168.91.135 
Last login: Mon Oct 10 01:25:49 2016 from 192.168.91.133 
[root@localhost ~]# 

常见错误:

[root@test ~]# ssh-copy-id -i ~/.ssh/id_rsa.pub 192.168.91.135
-bash: ssh-copy-id: command not found //提示命令不存在

解决办法:yum -y install openssh-clients

2.2 通过scp将内容写到对方的文件中

命令:scp -p ~/.ssh/id_rsa.pub root@:/root/.ssh/authorized_keys

举例:

[root@test .ssh]# scp -p ~/.ssh/id_rsa.pub root@192.168.91.135:/root/.ssh/authorized_keys
 root@192.168.91.135's password:  
id_rsa.pub 100% 408 0.4KB/s 00:00
  
[root@test .ssh]#   
[root@test .ssh]# ssh root@192.168.91.135
Last login: Mon Oct 10 01:27:02 2016 from 192.168.91.133 
[root@localhost ~]# 
2.3 通过Ansible实现批量免密

2.3.1 将需要做免密操作的机器hosts添加到/etc/ansible/hosts下:

[Avoid close]
192.168.91.132
192.168.91.133
192.168.91.134

2.3.2 执行命令进行免密操作

ansible -m authorized_key -a "user=root key='{{ lookup('file','/root/.ssh/id_rsa.pub') }}'" -k

示例:

[root@test sshpass-1.05]# ansible test -m authorized_key -a "user=root key='{{ lookup('file','/root/.ssh/id_rsa.pub') }}'" -k   
SSH password: ----->输入密码   192.168.91.135 | success >>{   
"changed": true,    
"key": "ssh-rsa AAAAB3NzaC1yc2EAAAABIwAAAQEArZI4kxlYuw7j1nt5ueIpTPWfGBJoZ8Mb02OJHR8yGW7A3izwT3/uhkK7RkaGavBbAlprp5bxp3i0TyNxa/apBQG5NiqhYO8YCuiGYGsQAGwZCBlNLF3gq1/18B6FV5moE/8yTbFA4dBQahdtVP PejLlSAbb5ZoGK8AtLlcRq49IENoXB99tnFVn3gMM0aX24ido1ZF9RfRWzfYF7bVsLsrIiMPmVNe5KaGL9kZ0svzoZ708yjWQQCEYWp0m+sODbtGPC34HMGAHjFlsC/SJffLuT/ug/hhCJUYeExHIkJF8OyvfC6DeF7ArI6zdKER7D8M0SM  WQmpKUltj2nltuv3w== root@localhost.localdomain",  
"key_options": null,    
"keyfile": "/root/.ssh/authorized_keys",    
"manage_dir": true,    
"path": null,    
"state": "present",    
"unique": false,    
"user": "root"  
}   
[root@test sshpass-1.05]# 
2.4 手工复制粘贴的方式

将本地id_rsa.pub文件的内容拷贝至远程服务器的~/.ssh/authorized_keys文件中

原文来自:http://www.jb51_net.ykhou.cn/article/94599.htm

本文地址:http://vishd.cn.www.linuxprobe.com/linux-ssh-withon-passwd.html编辑:陶武杰,审核员:逄增宝