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MySQL用戶和權限及破解root口令的方法示例

MySQL用戶和權限

在MySQL中有一個系統自身就帶有的數據庫叫MySQL，數據庫裝好以后系統自帶了好幾個數據庫MySQL就是其中過一個，MySQL數據庫有個用戶賬戶權限相關的表叫user表，在其中就有創建的用戶。

MySQL中完整的用戶名是由用戶+主機名形成，主機名決定了這個用戶在哪個主機上能登陸。

一、用戶的創建和密碼修改

1.用戶的創建

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

USERNAME:用戶名
HOST:主機地址
PASSWORD:密碼

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中有匿名賬戶，可以通過跑安全加固腳本mysql_secure_installation來進行刪除，也可以手動將其刪除。

刪除用戶：

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.密碼的修改

mysql密碼的修改

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

示例：

對masuri用戶做密碼的修改

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 |
+--------+-----------------------+-------------------------------------------+
#此時密碼已經發生改變

root賬號口令為空，為root口令設置口令，由于一條一條的設置太過麻煩也可以使用修改表的操作來修改密碼

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)

此時密碼已經修改但依舊無法登陸，需要將權限刷新

MariaDB [(none)]> FLUSH PRIVILEGES;
Query OK, 0 rows affected (0.00 sec)

二、MySQL權限管理

權限管理涉及到多種權限的類別，比如說有管理類、程序類、數據庫級別、表級別和字段級別

管理類：能否創建用戶，能否顯示數據庫列表，能否重新加載配置文件，能否關閉數據庫，和復制相關的能否執行，能否管理進程，能否創建臨時表，能否創建數據庫中的文件。

程序類主要涉及3個程序，函數，存儲過程和觸發器，例如能否創建，修改，刪除和執行這些程序庫，表和字段級別的權限：比如能否在庫，表字段里進行增、刪、查、改等操作

1.授權GRANT

授權用戶時如果用戶不存在可以將其創建出來，在授權前首先要確認自己是管理員有授權的權限。

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：

創建一個wordpress的用戶，并授權。

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.查看用戶的權限

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.授權的其他選項

MAX_QUESRIES_PER_HOUR count #每小時最多查多少次
MAX_UPDATES_PER_HOUR count #每小時最多改多少次
MAX_CONNECTIONS_PER_HOUR count #每小時最多連多少次
MAX_USER_CONNECTIONS count #用戶的最大數連接數

取消權限

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)
# 此時wpuser@'192.168.73.%'已經沒有了delete權限

MySQL的root口令破解

工作中有時候可能會遇到root口令丟失的情況，此時可以通過以下方法進行找回root口令

以下為示范如何破解root口令

一、密碼未知無法登陸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，添加兩行參數

skip_grant_tables:跳過授權表信息，此項生效后再次使用MySQL就無需使用密碼了，但是遠程的其他用戶也可以不使用密碼登陸，有一定的風險性

skip_networking:關閉網路功能，由于光啟用skip_grant_tables選項，其他用戶也可以無需密碼登陸MySQL非常危險，所以需要關閉網路功能只允許本地的用戶進行操作。

[root@localhost ~]# vim /etc/my.cnf
[mysqld]
skip_networking=on   #不啟用網絡功能
skip_grant_tables=on   #跳過授權表

[root@localhost ~]# service mysqld restart       #對位置文件修改后需要重新啟動服務
Restarting mysqld (via systemctl):       [ OK ]

2.登陸MySQL，進行密碼修改

[root@localhost ~]# mysql           #此時已經無需輸入密碼就能登陸
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';  #對root的口令進行修改
Query OK, 4 rows affected (0.01 sec)
Rows matched: 4 Changed: 4 Warnings: 0

3.口令修改完畢后，需要將配置文件恢復

將剛才啟用的兩個選項進行注銷或者刪除，然后重啟服務

[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.使用新口令登陸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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