Linux下如何配置ssh免密登录

SSH 是 Linux 系统的登录工具，现在广泛用于服务器登录和各种加密通信。

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：

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\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

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命令： ssh-copy-id -i ~/.ssh/id_rsa.put

举例：

[root@test .ssh]# ssh-copy-id -i ~/.ssh/id_rsa.pub 192.168.91.135root@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@192.168.91.135Last 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

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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_keysroot@192.168.91.135's password:  id_rsa.pub 100% 408 0.4KB/s 00:00 [root@test .ssh]#  [root@test .ssh]# ssh root@192.168.91.135Last 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]192.168.91.132192.168.91.133192.168.91.134

2.3.2 执行命令进行免密操作

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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