用户与授权：MySQL系列之六

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