linux笔记整理（8、9）

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######系统服务的控制######

1. systemd

程序初始化程序，系统开始的第一个进程，pid为1

2. systemctl命令

systemctl list-units //列出当前系统服务的状态

systemctl list-unit-files //列出服务的开机状态

systemctl status sshd //查看指定服务的状态

systemctl stop sshd //关闭指定服务

systemctl start sshd //开启指定服务

systemctl restart sshd //重新启动服务

systemctl enable sshd //设定指定服务开机开启

systemctl disable sshd //设定指定服务开机关闭

systemctl reload sshd //使指定服务重新加载配置

systemctl list-dependencies sshd //查看指定服务的依赖关系

systemctl mask sshd //冻结指定服务

systemctl unmask sshd //启用服务

systemctl set-default multi-user.target //开机不开启图形

systemctl set-default graphical.target //开机启动图形

3. 服务状态

systemctl status 服务名称

loaded //系统服务已经初始化完成，加载过配置

active(running) //正有一个或多个程序正在系统中执行，vsftpd就是这种模式

active(exited) //执行一次就正常结束的服务，

//目前并没有任何程序在系统中执行

active(waiting) //正在执行当中

inactive //服务关闭

enabled //服务开机启动

disabled //服务开启不自启

static //服务开机启动项不可被管理

####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

#####客户端连接方式#####

ssh 远程主机用户@远程主机ip

[root@desktop0 ~]# ssh root@172.25.0.11

The authenticity of host ‘172.25.0.11 (172.25.0.11)’ can’t beestablished.

ECDSA key fingerprint iseb:24:0e:07:96:26:b1:04:c2:37:0c:78:2d:bc:b0:08.

Are you sure you want to continue connecting (yes/no)? yes //链接陌生主机时需要建立认证关系

Warning: Permanently added ‘172.25.0.11’ (ECDSA) to the list ofknown host

root@172.25.0.11’s password: //远程用户密码

[root@server0 ~]# //登陆成功

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 command //直接在远程主机运行某条命令

#####sshkey加密#####

1. 生成公钥私钥

[root@server0 ~]# 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 root@server.example.com

The key’s randomart image is:

[root@server0 ~]# ls/root/.ssh

id_rsa id_rsa.pub

id_rsa //私钥，就是钥匙

id_rsa.pub //公钥，就是锁

2. 添加key认证方式

[root@server0 ~]# ssh-copy-id –i /root/.ssh/id_rsa.pub root@172.25.0.11

ssh-copy-id //添加key认证方式的工具

-i //指定加密key文件

/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

[root@sercer0 ~]# scp /root/.ssh/id_rsa.pub root@172.25.0.11

4. 测试

[root@desktop0 ~]# ssh root@172.25.0.11 //通过id_rsa直接连接不需要输入用户密码

Last login : Mon Oct 3 03:58:102016 from 172.25.0.250

[root@server0 ~]#

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