MySQL系列之六 用户与授权

一、用户管理

1、用户账号

用户的账号由用户名和host俩部分组成（'username'@'host'）

host的表示：

• 主机名
• 具体ip地址
• 网段/掩码

可以使用通配符表示，%和_；192.168.%即表示这个网段的所有主机

2、增加删除账号

主要：在数据库中修改了用户信息需要执行flush privileges;来刷新授权表使其生效

创建

  mariadb [mysql]> create user 'user1'@'192.168.%';
  mariadb [mysql]> create user 'user2'@'192.168.%' identified by 'your_password';
  mariadb [mysql]> select user,host,password from user;
  +-------+-----------+-------------------------------------------+
  | user  | host      | password                                  |
  +-------+-----------+-------------------------------------------+
  | root  | localhost | *4a54c3f37c03c7fbace31591d6a8c546f93df5c5 |
  | root  | centos7   |                                           |
  | root  | 127.0.0.1 |                                           |
  | root  | ::1       |                                           |
  |       | localhost |                                           |
  |       | centos7   |                                           |
  | user1 | 192.168.% |                                           |
  | user2 | 192.168.% | *9e72259ba9214f692a85b240647c4d95b0f2e08b |
  +-------+-----------+-------------------------------------------+

删除

  mariadb [mysql]> drop user user2@'192.168.%';
  mariadb [mysql]> select user,host,password from user;      
  +-------+-----------+-------------------------------------------+
  | user  | host      | password                                  |
  +-------+-----------+-------------------------------------------+
  | root  | localhost | *4a54c3f37c03c7fbace31591d6a8c546f93df5c5 |
  | root  | centos7   |                                           |
  | root  | 127.0.0.1 |                                           |
  | root  | ::1       |                                           |
  |       | localhost |                                           |
  |       | centos7   |                                           |
  | user1 | 192.168.% |                                           |
  +-------+-----------+-------------------------------------------+

重命名

  mariadb [mysql]> rename user user1@'192.168.%' to testuser@'%';
  mariadb [mysql]> select user,host,password from mysql.user;
  +----------+-----------+-------------------------------------------+
  | user     | host      | password                                  |
  +----------+-----------+-------------------------------------------+
  | root     | localhost | *4a54c3f37c03c7fbace31591d6a8c546f93df5c5 |
  | root     | centos7   |                                           |
  | root     | 127.0.0.1 |                                           |
  | root     | ::1       |                                           |
  |          | localhost |                                           |
  |          | centos7   |                                           |
  | testuser | %         |                                           |
  +----------+-----------+-------------------------------------------+

修改密码

  mariadb [mysql]> set password for testuser@'%' =password('testpass');
  mariadb [mysql]> select user,host,password from mysql.user;          
  +----------+-----------+-------------------------------------------+
  | user     | host      | password                                  |
  +----------+-----------+-------------------------------------------+
  | root     | localhost | *4a54c3f37c03c7fbace31591d6a8c546f93df5c5 |
  | root     | centos7   |                                           |
  | root     | 127.0.0.1 |                                           |
  | root     | ::1       |                                           |
  |          | localhost |                                           |
  |          | centos7   |                                           |
  | testuser | %         | *00e247ac5f9af26ae0194b41e1e769dee1429a29 |
  +----------+-----------+-------------------------------------------+

其他修改密码的方法：

​ update user set password=password('testpass') where user='testuser';

​ # mysqladmin -uroot -poldpass password 'newpass'

3、破解管理账号密码

空数据库的情况下恢复密码

  # systemctl stop mariadb
  # rm -rf /var/lib/mysql/*  #删库跑路
  # systemctl start mariadb

有数据的情况下恢复密码

  1）在/etc/my.cnf配置文件的[mydqld]下添加skip-grant-tables和skip-networking参数

  2）# systemctl restart mariadb 重启服务

  3）执行mysql登录到数据库

  4）mariadb [(none)]> update mysql.user set password=password('newpassword') where user='root' and host='localhost';  #更新密码

  5）mariadb [(none)]> flush privileges;  #刷新授权表

  6）退出，修改配置文件，删除skip-grant-tables和skip-networking参数，重启服务
也可以在启动mysqld进程时，为其使用如下选项：

--skip-grant-tables

​ --skip-networking

二、授权管理

1、授权

​ 语法：grant priv_type on [object_type] priv_level to user@'%' [identified by 'password'] [with grant option];

授权时如果用户不存在则创建，所以我们一般不会单独去创建一个用户，而是授权创建一块完成。

priv_type 授权类型

- select

- ​insert

- ​update

- ​delete

- ​create

- ​drop

- index

- alter

- ​show databases

- ​create temporary tables

- ​lock tables

- ​create view

- show view

- create user

- all privileges 或 all

object_type 授权对象

- table

- function

- procedure

priv_level 授权级别

- *或*.* 表示所有库

- db_name.* 表示指定库中的所有表

- db_name.tbl_name 指定库中的指定表

- tbl_name 表示当前库的表

- db_name.routine_name 表示指定库的函数,存储过程,触发器

with grant option

- max_queries_per_hour count

- max_updates_per_hour count

- max_connections_per_hour count

- max_user_connections count

mariadb [school]> grant select(stuid,name) on table school.students to admin@'%' identified by 'admin';  #把students表的stuid和name字段的查询权限授权于admin@'%'用户
mariadb [school]> flush privileges;  #刷新授权表

2、查询授权

mariadb [school]> show grants for admin@'%'\g  #查看指定用户的权限
*************************** 1. row ***************************
grants for admin@%: grant usage on *.* to 'admin'@'%' identified by password '*4acfe3202a5ff5cf467898fc58aab1d615029441'
*************************** 2. row ***************************
grants for admin@%: grant select (stuid, name) on `school`.`students` to 'admin'@'%'

[root@working ~]# mysql -uadmin -padmin -h192.168.0.7
mariadb [(none)]> show grants for current_user()\g  #查询自己的权限
*************************** 1. row ***************************
grants for admin@%: grant usage on *.* to 'admin'@'%' identified by password '*4acfe3202a5ff5cf467898fc58aab1d615029441'
*************************** 2. row ***************************
grants for admin@%: grant select (stuid, name) on `school`.`students` to 'admin'@'%'

3、收回授权

mariadb [school]> revoke select(stuid) on school.students from admin@'%';  #收回admin@'%'用户对stuid字段的查询权限

总结

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