MySQL用户和权限及破解root口令的方法示例

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)]> 

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