前言
最近在工作中遇到一個需求：修改MySQL用戶的權限，需要限制特定IP地址才能訪問，第一次遇到這類需求，結果在測試過程，使用更新系統權限報發現出現了一些問題， 具體演示如下.
注意：下面測試環境為MySQL 5.6.20. 如有其它版本與下面測試結果有出入，請以實際環境為準。
我們先創建一個測試用戶LimitIP，只允許192.168段的IP地址訪問，具體權限如下所示：
mysql> GRANT SELECT ON MyDB.* TO LimitIP@'192.168.%' IDENTIFIED BY 'LimitIP';Query OK, 0 rows affected (0.01 sec) mysql> GRANT INSERT ,UPDATE,DELETE ON MyDB.kkk TO LimitIP@'192.168.%';Query OK, 0 rows affected (0.00 sec) mysql> mysql> flush privileges;Query OK, 0 rows affected (0.00 sec) mysql> mysql> show grants for LimitIP@'192.168.%';+----------------------------------------------------------------------------------------------------------------+| Grants for LimitIP@192.168.% |+----------------------------------------------------------------------------------------------------------------+| GRANT USAGE ON *.* TO 'LimitIP'@'192.168.%' IDENTIFIED BY PASSWORD '*72DDE03E02CC55A9478A82F3F4EBE7F639249DEC' || GRANT SELECT ON `MyDB`.* TO 'LimitIP'@'192.168.%' || GRANT INSERT, UPDATE, DELETE ON `MyDB`.`kkk` TO 'LimitIP'@'192.168.%' |+----------------------------------------------------------------------------------------------------------------+3 rows in set (0.00 sec) mysql>
假設現在收到需求：這個用戶只允許這個IP地址192.168.103.17訪問，于是我打算更新mysql.user表，如下所示：
mysql> select user, host from mysql.user where user='LimitIP';+---------+-----------+| user | host |+---------+-----------+| LimitIP | 192.168.% |+---------+-----------+1 row in set (0.00 sec) mysql> update mysql.user set host='192.168.103.17' where user='LimitIP';Query OK, 1 row affected (0.02 sec)Rows matched: 1 Changed: 1 Warnings: 0 mysql> flush privileges;Query OK, 0 rows affected (0.01 sec) mysql> select user, host from user where user='LimitIP';ERROR 1046 (3D000): No database selectedmysql> use mysql;Reading table information for completion of table and column namesYou can turn off this feature to get a quicker startup with -A Database changedmysql> select user, host from user where user='LimitIP';+---------+----------------+| user | host |+---------+----------------+| LimitIP | 192.168.103.17 |+---------+----------------+1 row in set (0.00 sec) mysql> show grants for LimitIP@'192.168.103.17';+---------------------------------------------------------------------------------------------------------------------+| Grants for LimitIP@192.168.103.17 |+---------------------------------------------------------------------------------------------------------------------+| GRANT USAGE ON *.* TO 'LimitIP'@'192.168.103.17' IDENTIFIED BY PASSWORD '*72DDE03E02CC55A9478A82F3F4EBE7F639249DEC' |+---------------------------------------------------------------------------------------------------------------------+1 row in set (0.00 sec) mysql>
上面測試發現，如果這樣只修改mysql.user表， 那么之前的權限沒有了，如下所示，如果你查詢mysql.db、 mysql.tables_priv 發現Host的字段值依然為192.168.%
mysql> select * from mysql.db where user='LimitIP'/G;*************************** 1. row *************************** Host: 192.168.% Db: MyDB User: LimitIP Select_priv: Y Insert_priv: N Update_priv: N Delete_priv: N Create_priv: N Drop_priv: N Grant_priv: N References_priv: N Index_priv: N Alter_priv: NCreate_tmp_table_priv: N Lock_tables_priv: N Create_view_priv: N Show_view_priv: N Create_routine_priv: N Alter_routine_priv: N Execute_priv: N Event_priv: N Trigger_priv: N1 row in set (0.00 sec) ERROR: No query specified mysql> select * from mysql.tables_priv where user='LimitIP'/G;*************************** 1. row *************************** Host: 192.168.% Db: MyDB User: LimitIP Table_name: kkk Grantor: root@localhost Timestamp: 0000-00-00 00:00:00 Table_priv: Insert,Update,DeleteColumn_priv: 1 row in set (0.00 sec) ERROR: No query specified
所以我繼續修改 mysql.db、 mysql.tables_priv 表，然后測試驗證終于OK了（請見下面測試步驟），當然如果賬戶的權限不止這幾個層面，你可能還必須修改例如mysql.columns_priv、mysql.procs_priv等表
mysql> show grants for LimitIP@'192.168.%';ERROR 1141 (42000): There is no such grant defined for user 'LimitIP' on host '192.168.%'mysql> mysql> mysql> update mysql.db set host='192.168.103.17' where user='LimitIP';Query OK, 1 row affected (0.00 sec)Rows matched: 1 Changed: 1 Warnings: 0 mysql> update mysql.tables_priv set host='192.168.103.17' where user='LimitIP';Query OK, 1 row affected (0.00 sec)Rows matched: 1 Changed: 1 Warnings: 0 mysql> flush privileges;Query OK, 0 rows affected (0.00 sec) mysql> show grants for LimitIP@'192.168.103.17';+---------------------------------------------------------------------------------------------------------------------+| Grants for LimitIP@192.168.103.17 |+---------------------------------------------------------------------------------------------------------------------+| GRANT USAGE ON *.* TO 'LimitIP'@'192.168.103.17' IDENTIFIED BY PASSWORD '*72DDE03E02CC55A9478A82F3F4EBE7F639249DEC' || GRANT SELECT ON `MyDB`.* TO 'LimitIP'@'192.168.103.17' || GRANT INSERT, UPDATE, DELETE ON `MyDB`.`kkk` TO 'LimitIP'@'192.168.103.17' |+---------------------------------------------------------------------------------------------------------------------+3 rows in set (0.00 sec) mysql>
如果需要修改用戶的IP限制，其實更新mysql相關權限表不是上上策，其實有更好的方法，那就是RENAME USER Syntax
mysql> RENAME USER 'LimitIP'@'192.168.103.17' TO 'LimitIP'@'192.168.103.18';Query OK, 0 rows affected (0.00 sec) mysql> FLUSH PRIVILEGES;Query OK, 0 rows affected (0.00 sec) mysql> show grants for 'LimitIP'@'192.168.103.18';+---------------------------------------------------------------------------------------------------------------------+| Grants for LimitIP@192.168.103.18 |+---------------------------------------------------------------------------------------------------------------------+| GRANT USAGE ON *.* TO 'LimitIP'@'192.168.103.18' IDENTIFIED BY PASSWORD '*72DDE03E02CC55A9478A82F3F4EBE7F639249DEC' || GRANT SELECT ON `MyDB`.* TO 'LimitIP'@'192.168.103.18' || GRANT INSERT, UPDATE, DELETE ON `MyDB`.`kkk` TO 'LimitIP'@'192.168.103.18' |+---------------------------------------------------------------------------------------------------------------------+3 rows in set (0.00 sec) mysql>
總結
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