MySQL用户和权限

在MySQL中有一个系统自身就带有的数据库叫MySQL,数据库装好以后系统自带了好几个数据库MySQL就是其中过一个,MySQL数据库有个用户账户权限相关的表叫user表,在其中就有创建的用户。
MySQL中完整的用户名是由用户+主机名形成,主机名决定了这个用户在哪个主机上能登陆。

一、用户的创建和密码修改

1.用户的创建

    create user 'USERNAME'@'HOST' identified by 'PASSWORD';

USERNAME:用户名
HOST:主机地址
PASSWORD:密码
示例:

MariaDB [(none)]> create user masuri@192.168.73.133 identified by 'centos';
Query OK, 0 rows affected (0.01 sec)

MariaDB [(none)]> select user,host,password from mysql.user;
+--------+-----------------------+-------------------------------------------+
| user   | host                  | password                                  |
+--------+-----------------------+-------------------------------------------+
| root   | localhost             |                                           |
| root   | localhost.localdomain |                                           |
| root   | 127.0.0.1             |                                           |
| root   | ::1                   |                                           |
|        | localhost             |                                           |
|        | localhost.localdomain |                                           |
| masuri | 192.168.73.133        | *128977E278358FF80A246B5046F51043A2B1FCED |
+--------+-----------------------+-------------------------------------------+
7 rows in set (0.00 sec)

MySQL中有匿名账户,可以通过跑安全加固脚本mysql_secure_installation来进行删除,也可以手动将其删除。
删除用户:

DROP USER 'USERNAME'@'HOST';

示例:

MariaDB [(none)]> select user,host,password from mysql.user;
+--------+-----------------------+-------------------------------------------+
| user   | host                  | password                                  |
+--------+-----------------------+-------------------------------------------+
| root   | localhost             |                                           |
| root   | localhost.localdomain |                                           |
| root   | 127.0.0.1             |                                           |
| root   | ::1                   |                                           |
|        | localhost             |                                           |
|        | localhost.localdomain |                                           |
| masuri | 192.168.73.133        | *128977E278358FF80A246B5046F51043A2B1FCED |
+--------+-----------------------+-------------------------------------------+
7 rows in set (0.00 sec)

MariaDB [(none)]> DROP USER ''@'localhost';
Query OK, 0 rows affected (0.00 sec)

MariaDB [(none)]> DROP USER ''@'localhost.localdomain';
Query OK, 0 rows affected (0.00 sec)

MariaDB [(none)]> select user,host,password from mysql.user;
+--------+-----------------------+-------------------------------------------+
| user   | host                  | password                                  |
+--------+-----------------------+-------------------------------------------+
| root   | localhost             |                                           |
| root   | localhost.localdomain |                                           |
| root   | 127.0.0.1             |                                           |
| root   | ::1                   |                                           |
| masuri | 192.168.73.133        | *128977E278358FF80A246B5046F51043A2B1FCED |
+--------+-----------------------+-------------------------------------------+
5 rows in set (0.00 sec)

2.密码的修改
mysql密码的修改

SET PASSWORD FOR user = PASSWORD('cleartext password')
UPDATE table SET password = password('cleartext password')

示例:
对masuri用户做密码的修改

MariaDB [(none)]> SET PASSWORD FOR masuri@192.168.73.133 = PASSWORD ('magedu');
Query OK, 0 rows affected (0.00 sec)

MariaDB [(none)]> select user,host,password from mysql.user;
+--------+-----------------------+-------------------------------------------+
| user   | host                  | password                                  |
+--------+-----------------------+-------------------------------------------+
| root   | localhost             |                                           |
| root   | localhost.localdomain |                                           |
| root   | 127.0.0.1             |                                           |
| root   | ::1                   |                                           |
| masuri | 192.168.73.133        | *6B8CCC83799A26CD19D7AD9AEEADBCD30D8A8664 |
+--------+-----------------------+-------------------------------------------+
#此时密码已经发生改变

root账号口令为空,为root口令设置口令,由于一条一条的设置太过麻烦也可以使用修改表的操作来修改密码

MariaDB [(none)]> update mysql.user set password=password('centos') where user='root';
Query OK, 4 rows affected (0.01 sec)
Rows matched: 4  Changed: 4  Warnings: 0

MariaDB [(none)]> select user,host,password from mysql.user;
+--------+-----------------------+-------------------------------------------+
| user   | host                  | password                                  |
+--------+-----------------------+-------------------------------------------+
| root   | localhost             | *128977E278358FF80A246B5046F51043A2B1FCED |
| root   | localhost.localdomain | *128977E278358FF80A246B5046F51043A2B1FCED |
| root   | 127.0.0.1             | *128977E278358FF80A246B5046F51043A2B1FCED |
| root   | ::1                   | *128977E278358FF80A246B5046F51043A2B1FCED |
| masuri | 192.168.73.133        | *6B8CCC83799A26CD19D7AD9AEEADBCD30D8A8664 |
+--------+-----------------------+-------------------------------------------+
5 rows in set (0.00 sec)
此时密码已经修改但依旧无法登陆,需要将权限刷新
MariaDB [(none)]> FLUSH PRIVILEGES;
Query OK, 0 rows affected (0.00 sec)

二、MySQL权限管理

权限管理涉及到多种权限的类别,比如说有管理类、程序类、数据库级别、表级别和字段级别
管理类:能否创建用户,能否显示数据库列表,能否重新加载配置文件,能否关闭数据库,和复制相关的能否执行,能否管理进程,能否创建临时表,能否创建数据库中的文件。
程序类主要涉及3个程序,函数,存储过程和触发器,例如能否创建,修改,删除和执行这些程序
库,表和字段级别的权限:比如能否在库,表字段里进行增、删、查、改等操作

1.授权GRANT

授权用户时如果用户不存在可以将其创建出来,在授权前首先要确认自己是管理员有授权的权限。

GRANT 
    priv_type [(column_list)]
      [, priv_type [(column_list)]] ...
    ON [object_type] priv_level
    TO user_specification [, user_specification] ...
    [REQUIRE {NONE | ssl_option [[AND] ssl_option] ...}]
    [WITH with_option ...]

示例:
创建一个wordpress的用户,并授权。

MariaDB [(none)]> CREATE DATABASE wordpress;
Query OK, 1 row affected (0.02 sec)

MariaDB [(none)]> GRANT ALL ON wordpress.* TO wpuser@'192.168.73.%' identified by 'mylinuxops';
Query OK, 0 rows affected (0.00 sec)

2.查看用户的权限

MariaDB [(none)]> show grants for wpuser@'192.168.73.%';
+------------------------------------------------------------------------------------------------------------------+
| Grants for wpuser@192.168.73.%                                                                                   |
+------------------------------------------------------------------------------------------------------------------+
| GRANT USAGE ON *.* TO 'wpuser'@'192.168.73.%' IDENTIFIED BY PASSWORD '*EC0DBFB480593BB6ED2EC028A4231A72D8137406' |
| GRANT ALL PRIVILEGES ON `wordpress`.* TO 'wpuser'@'192.168.73.%'                                                 |
+------------------------------------------------------------------------------------------------------------------+
2 rows in set (0.00 sec)

3.授权的其他选项

MAX_QUESRIES_PER_HOUR count   #每小时最多查多少次
MAX_UPDATES_PER_HOUR count    #每小时最多改多少次
MAX_CONNECTIONS_PER_HOUR count #每小时最多连多少次
MAX_USER_CONNECTIONS count    #用户的最大数连接数

取消权限

REVOKE
    priv_type [(column_list)]
      [, priv_type [(column_list)]] ...
    ON [object_type] priv_level
    FROM user [, user] ...

示例:

MariaDB [(none)]> revoke delete on wordpress.* from wpuser@'192.168.73.%';
Query OK, 0 rows affected (0.00 sec)

MariaDB [(none)]> show grants for wpuser@'192.168.73.%';
+----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
| Grants for wpuser@192.168.73.%                                                                                                                                                                                                         |
+----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
| GRANT USAGE ON *.* TO 'wpuser'@'192.168.73.%' IDENTIFIED BY PASSWORD '*EC0DBFB480593BB6ED2EC028A4231A72D8137406'                                                                                                                       |
| GRANT SELECT, INSERT, UPDATE, CREATE, DROP, REFERENCES, INDEX, ALTER, CREATE TEMPORARY TABLES, LOCK TABLES, EXECUTE, CREATE VIEW, SHOW VIEW, CREATE ROUTINE, ALTER ROUTINE, EVENT, TRIGGER ON `wordpress`.* TO 'wpuser'@'192.168.73.%' |
+----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
2 rows in set (0.00 sec)
# 此时wpuser@'192.168.73.%'已经没有了delete权限

MySQL的root口令破解

工作中有时候可能会遇到root口令丢失的情况,此时可以通过以下方法进行找回root口令
以下为示范如何破解root口令
一、密码未知无法登陆MySQL

[root@localhost ~]# mysql
ERROR 1045 (28000): Access denied for user 'root'@'localhost' (using password: NO)

二、破解
1.修改配置文件/etc/my.cnf,添加两行参数
skip_grant_tables:跳过授权表信息,此项生效后再次使用MySQL就无需使用密码了,但是远程的其他用户也可以不使用密码登陆,有一定的风险性
skip_networking:关闭网路功能,由于光启用skip_grant_tables选项,其他用户也可以无需密码登陆MySQL非常危险,所以需要关闭网路功能只允许本地的用户进行操作。

[root@localhost ~]# vim /etc/my.cnf
[mysqld]
skip_networking=on            #不启用网络功能
skip_grant_tables=on          #跳过授权表

[root@localhost ~]# service mysqld restart                            #对位置文件修改后需要重新启动服务
Restarting mysqld (via systemctl):                         [  OK  ]

2.登陆MySQL,进行密码修改

[root@localhost ~]# mysql                                           #此时已经无需输入密码就能登陆
Welcome to the MariaDB monitor.  Commands end with ; or \g.
Your MariaDB connection id is 11
Server version: 10.2.23-MariaDB-log Source distribution

Copyright (c) 2000, 2018, Oracle, MariaDB Corporation Ab and others.

Type 'help;' or '\h' for help. Type '\c' to clear the current input statement.

MariaDB [(none)]> UPDATE mysql.user SET password=PASSWORD('123456') where user='root';        #对root的口令进行修改
Query OK, 4 rows affected (0.01 sec)
Rows matched: 4  Changed: 4  Warnings: 0

3.口令修改完毕后,需要将配置文件恢复
将刚才启用的两个选项进行注销或者删除,然后重启服务

[root@localhost ~]# vim /etc/my.cnf
[mysqld]
#skip_networking=on            
#skip_grant_tables=on          

[root@localhost ~]# service mysqld restart
Restarting mysqld (via systemctl):                         [  OK  ]

4.使用新口令登陆MySQL

[root@localhost ~]# mysql -uroot -p123456 
Welcome to the MariaDB monitor.  Commands end with ; or \g.
Your MariaDB connection id is 10
Server version: 10.2.23-MariaDB-log Source distribution

Copyright (c) 2000, 2018, Oracle, MariaDB Corporation Ab and others.

Type 'help;' or '\h' for help. Type '\c' to clear the current input statement.

MariaDB [(none)]>