Linux unit9

Posted 2020-09-09

1.openssh-server

功能：让远程主机可以通过网络访问sshd服务，开始一个安全shell

 

2.客户端连接方式

ssh 远程主机用户@远程主机ip -X##调用远程主机图形工具

ssh远程主机用户@远程主机ip       ssh [email protected]172.25.0.11（自己的ip）

 

ssh     远程主机用户@远程主机ipcommand##直接在远程主机运行某条命令

 

3.sshkey加密

1）生成公钥私钥        ssh-keygen ##生成公钥私钥工具

Generating public/private rsa key pair.

Enter file in which to save the key (/root/.ssh/id_rsa):[enter] ##加密字符保存文件（建议用默认）

Created directory ‘/root/.ssh‘.

Enter passphrase (empty for no passphrase): [enter]##密钥密码，必须>4个字符

Enter same passphrase again: [enter]##确认密码

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:

ab:3c:73:2e:c8:0b:75:c8:39:3a:46:a2:22:34:84:81 [email protected]

The key‘s randomart image is:

+--[ RSA 2048]----+

|o                |

|E.               |

|..               |

|.  . o           |

|.o. * . S        |     

|oo.o o   .       |

|+ =. .  .        |

|o. oo.+..        |

|    ..o*.        |

+-----------------+

 

 

[[email protected] ~]# ls /root/.ssh/

id_rsa##私钥，就是钥匙

id_rsa.pub##公钥，就是锁

 

2）添加key认证方式   ssh-copy-id ##添加key认证方式的工具   -i##指定加密key文件

加密命令： ssh-copy-id -i /root/.ssh/id_rsa.pub  [email protected]

/root/.ssh/id_rsa.pub##加密key    root##加密用户为root

172.25.0.11##被加密主机ip

 

3）分发钥匙给client主机

命令： scp /root/.ssh/id_rsa [email protected]:/root/.ssh/

 

4）测试

 

[[email protected] ~]# ssh [email protected]##通过id_rsa直接连接不需要输入用户密码

Last login: Mon Oct  3 03:58:10 2016 from 172.25.0.250

[[email protected] ~]#

 

4.提升openssh的安全级别

1）openssh-server配置文件

/etc/ssh/sshd_config

78 PasswordAuthentication yes|no##是否开启用户密码认证，yes为支持no为关闭

48 PermitRootLogin yes|no##是否允许超级用户登陆

49 AllowUsers student westos##用户白名单，只有在名单中出现的用户可以使用sshd建立shell

50 DenyUsers westos##用户黑名单

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