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如何理解MySQL管理基礎(chǔ)中的安全、訪問(wèn)控制和權(quán)限,很多新手對(duì)此不是很清楚,為了幫助大家解決這個(gè)難題,下面小編將為大家詳細(xì)講解,有這方面需求的人可以來(lái)學(xué)習(xí)下,希望你能有所收獲。
MySQL權(quán)限系統(tǒng)確保所有的用戶只執(zhí)行允許的操作。當(dāng)連接MySQL服務(wù)器時(shí),用戶身份由其所在的主機(jī)和使用的用戶名來(lái)決定。當(dāng)用戶在連接后發(fā)出請(qǐng)求時(shí),系統(tǒng)根據(jù)其身份和要進(jìn)行的操作來(lái)授予權(quán)限。
1.MySQL授權(quán)表
1)user表
mysql> select host, user, password from mysql.user;
+-----------+------+-------------------------------------------+
| host | user | password |
+-----------+------+-------------------------------------------+
| localhost | root | *25B0A985780CE19647D8E41C2B50E7FB300EA6E8 |
| % | root | *25B0A985780CE19647D8E41C2B50E7FB300EA6E8 |
+-----------+------+-------------------------------------------+
2 rows in set (0.00 sec)
注:“%”用作通配符,這里表示允許從任何主機(jī)以root用戶訪問(wèn)。除db表外的其它授權(quán)表中,空host值與“%”相同。
[@more@]MySQL授權(quán)表一般都包含兩類字段:范圍字段和權(quán)限字段。上面看到的user表的host、user、password屬于范圍字段,此外還有一些名稱以“_priv”結(jié)尾的權(quán)限字段,用于指定用戶擁有的權(quán)限。這里賦予用戶的權(quán)限適用于系統(tǒng)的每個(gè)數(shù)據(jù)庫(kù),因此一般將它們都設(shè)置為N,而使用host和db表進(jìn)行更為精細(xì)的權(quán)限設(shè)置。其余字段則與SSL加密以及用戶資源限制有關(guān)。
2)db和host表
db表有三個(gè)范圍字段host、db和user,指定該條記錄是針對(duì)某用戶從某主機(jī)連接某數(shù)據(jù)庫(kù)而言的;其余的字段為權(quán)限字段。
host有兩個(gè)范圍字段host、db,其余的字段為權(quán)限字段。如果db表中記錄的host字段留空,MySQL服務(wù)器在驗(yàn)證用戶權(quán)限時(shí)會(huì)從host表中獲取相應(yīng)的主機(jī)名。host表不受GRANT和REVOKE語(yǔ)句的影響。大多數(shù)MySQL安裝根本不需要使用該表。
3)tables_priv和columns_priv表
這兩個(gè)表可以分別限制對(duì)數(shù)據(jù)庫(kù)中具體的表和表中具體的列的訪問(wèn)。
當(dāng)MySQL需要決定是否允許用戶執(zhí)行某一數(shù)據(jù)庫(kù)操作時(shí),首先要查看user表中該用戶是否具有足夠的權(quán)限,如果沒(méi)有,再查看db和host表。一些管理操作,如RELOAD、PROCESS涉及整個(gè)系統(tǒng),只有user表中有相應(yīng)的列。
可以手工修改授權(quán)表的內(nèi)容來(lái)進(jìn)行權(quán)限設(shè)置(但tables_priv和columns_priv表不建議這樣做),修改后需要使用FLUSH PRIVILEGES語(yǔ)句、mysqladmin flush-privileges或mysqladmin reload命令重新裝載授權(quán)表。
2.授予和回收權(quán)限
通常使用GRANT和REVOKE命令授予和回收用戶的權(quán)限,下面通過(guò)一些例子來(lái)演示它們的用法。
首先,創(chuàng)建一個(gè)從本機(jī)連接MySQL服務(wù)器的ggyy用戶:
mysql> create user ggyy@localhost identified by 'password';
Query OK, 0 rows affected (0.00 sec)
mysql> select host, user from mysql.user;
+-----------+------+
| host | user |
+-----------+------+
| % | root |
| localhost | ggyy |
| localhost | root |
+-----------+------+
3 rows in set (0.00 sec)
現(xiàn)在可以使用ggyy用戶連接服務(wù)器,但還沒(méi)有訪問(wèn)數(shù)據(jù)庫(kù)的權(quán)限。
C:>mysql -u ggyy -p
Enter password: ****
Welcome to the MySQL monitor. Commands end with ; or g.
Your MySQL connection id is 18
Server version: 5.1.34-community MySQL Community Server (GPL)
Type 'help;' or 'h' for help. Type 'c' to clear the current input statement.
mysql> show databases;
+--------------------+
| Database |
+--------------------+
| information_schema |
+--------------------+
1 row in set (0.00 sec)
下面授予ggyy用戶在ggyy數(shù)據(jù)庫(kù)上的查詢權(quán)限:
mysql> select current_user();
+----------------+
| current_user() |
+----------------+
| root@localhost |
+----------------+
1 row in set (0.00 sec)
mysql> grant select on ggyy.* to ggyy@localhost;
Query OK, 0 rows affected (0.00 sec)
mysql> show grants for ggyy@localhost;
+-------------------------------------------------------------------------------------------------------------+
| Grants for ggyy@localhost |
+-------------------------------------------------------------------------------------------------------------+
| GRANT USAGE ON *.* TO 'ggyy'@'localhost' IDENTIFIED BY PASSWORD '*484FFAA42C12F40931C794D33A11B7F075B91467' |
| GRANT SELECT ON `ggyy`.* TO 'ggyy'@'localhost' |
+-------------------------------------------------------------------------------------------------------------+
2 rows in set (0.00 sec)
mysql> select host, db, user, select_priv, insert_priv, update_priv, delete_priv from mysql.db;
+-----------+------+------+-------------+-------------+-------------+-------------+
| host | db | user | select_priv | insert_priv | update_priv | delete_priv |
+-----------+------+------+-------------+-------------+-------------+-------------+
| localhost | ggyy | ggyy | Y | N | N | N |
+-----------+------+------+-------------+-------------+-------------+-------------+
1 row in set (0.00 sec)
mysql> select * from mysql.tables_priv;
Empty set (0.00 sec)
使用ggyy用戶查看ggyy數(shù)據(jù)庫(kù)中的內(nèi)容:
mysql> select current_user();
+----------------+
| current_user() |
+----------------+
| ggyy@localhost |
+----------------+
1 row in set (0.00 sec)
mysql> use ggyy
Database changed
mysql> show tables;
+----------------+
| Tables_in_ggyy |
+----------------+
| blob_text_test |
| char_test |
| contact |
| date_time_test |
| float_test |
| groups1 |
| groups2 |
| int_test |
| members |
| members_temp |
| processes1 |
| test_crttb |
| test_crttb2 |
| test_crttb3 |
| test_crttb4 |
| test_crttb5 |
| ts_dt_test |
| users1 |
+----------------+
18 rows in set (0.00 sec)
mysql> select * from processes1 limit 1;
+------+-------+------+
| pid | pname | ppid |
+------+-------+------+
| 1 | init | 0 |
+------+-------+------+
1 row in set (0.00 sec)
接下來(lái),再創(chuàng)建一個(gè)從遠(yuǎn)程主機(jī)192.168.7.100連接MySQL服務(wù)器的ggyy用戶,授予查詢ggyy數(shù)據(jù)庫(kù)中user1表的權(quán)限。使用GRANT命令可以在授權(quán)時(shí)創(chuàng)建被授權(quán)的用戶:
mysql> select current_user();
+----------------+
| current_user() |
+----------------+
| root@localhost |
+----------------+
1 row in set (0.00 sec)
mysql> grant select on ggyy.users1 to ggyy@192.168.7.100 identified by 'ggyy';
Query OK, 0 rows affected (0.00 sec)
mysql> show grants for ggyy@192.168.7.100;
+-----------------------------------------------------------------------------------------------------------------+
| Grants for ggyy@192.168.7.100 |
+-----------------------------------------------------------------------------------------------------------------+
| GRANT USAGE ON *.* TO 'ggyy'@'192.168.7.100' IDENTIFIED BY PASSWORD '*484FFAA42C12F40931C794D33A11B7F075B91467' |
| GRANT SELECT ON `ggyy`.`users1` TO 'ggyy'@'192.168.7.100' |
+-----------------------------------------------------------------------------------------------------------------+
2 rows in set (0.00 sec)
mysql> select host, user from mysql.user;
+---------------+------+
| host | user |
+---------------+------+
| % | root |
| 192.168.7.100 | ggyy |
| localhost | ggyy |
| localhost | root |
+---------------+------+
4 rows in set (0.00 sec)
mysql> select host, db, user, select_priv, insert_priv, update_priv, delete_priv from mysql.db where host = '192.168.7.1
00';
Empty set (0.00 sec)
mysql> select * from mysql.tables_priv where host = '192.168.7.100';
+---------------+------+------+------------+----------------+---------------------+------------+-------------+
| Host | Db | User | Table_name | Grantor | Timestamp | Table_priv | Column_priv |
+---------------+------+------+------------+----------------+---------------------+------------+-------------+
| 192.168.7.100 | ggyy | ggyy | users1 | root@localhost | 2010-01-17 14:02:42 | Select | |
+---------------+------+------+------------+----------------+---------------------+------------+-------------+
1 row in set (0.00 sec)
可以看到,由于授予的是表的權(quán)限,host表中沒(méi)有相應(yīng)記錄,需要到tables_priv表中查看。
在遠(yuǎn)程主機(jī)上訪問(wèn)數(shù)據(jù)庫(kù):
C:>mysql -h 192.168.7.101 -u ggyy -p
Enter password: ****
Welcome to the MySQL monitor. Commands end with ; or g.
Your MySQL connection id is 20
Server version: 5.1.34-community MySQL Community Server (GPL)
Type 'help;' or 'h' for help. Type 'c' to clear the current input statement.
mysql> select current_user();
+--------------------+
| current_user() |
+--------------------+
| ggyy@192.168.7.100 |
+--------------------+
1 row in set (0.00 sec)
mysql> show databases;
+--------------------+
| Database |
+--------------------+
| information_schema |
| ggyy |
+--------------------+
2 rows in set (0.00 sec)
mysql> use ggyy
Database changed
mysql> show tables;
+----------------+
| Tables_in_ggyy |
+----------------+
| users1 |
+----------------+
1 row in set (0.00 sec)
mysql> select * from users1 limit 1;
+------+----------+------+
| uid | uname | gid |
+------+----------+------+
| 202 | fengsong | 200 |
+------+----------+------+
1 row in set (0.00 sec)
要回收權(quán)限使用REVOKE命令,例如:
mysql> select current_user();
+----------------+
| current_user() |
+----------------+
| root@localhost |
+----------------+
1 row in set (0.00 sec)
mysql> revoke select on ggyy.* from ggyy@localhost;
Query OK, 0 rows affected (0.00 sec)
mysql> revoke select on ggyy.users1 from ggyy@192.168.7.100;
Query OK, 0 rows affected (0.00 sec)
也可以采用db和host表相結(jié)合的方式管理數(shù)據(jù)庫(kù)的權(quán)限,例如:
mysql> select current_user();
+----------------+
| current_user() |
+----------------+
| root@localhost |
+----------------+
1 row in set (0.00 sec)
mysql> insert into mysql.db (db, user, select_priv, delete_priv) values ('ggyy', 'ggyy', 'Y', 'Y');
Query OK, 1 row affected (0.00 sec)
mysql> insert into mysql.host (db, host, select_priv, insert_priv) values ('ggyy', 'localhost', 'Y', 'Y');
Query OK, 1 row affected (0.00 sec)
mysql> select host, db, user, select_priv, insert_priv, delete_priv from mysql.db where db = 'ggyy';
+------+------+------+-------------+-------------+-------------+
| host | db | user | select_priv | insert_priv | delete_priv |
+------+------+------+-------------+-------------+-------------+
| | ggyy | ggyy | Y | N | Y |
+------+------+------+-------------+-------------+-------------+
1 row in set (0.00 sec)
mysql> select host, db, select_priv, insert_priv, delete_priv from mysql.host where db = 'ggyy';
+-----------+------+-------------+-------------+-------------+
| host | db | select_priv | insert_priv | delete_priv |
+-----------+------+-------------+-------------+-------------+
| localhost | ggyy | Y | Y | N |
+-----------+------+-------------+-------------+-------------+
1 row in set (0.00 sec)
mysql> flush privileges;
Query OK, 0 rows affected (0.00 sec)
使用ggyy用戶在本機(jī)上訪問(wèn)數(shù)據(jù)庫(kù):
mysql> select current_user();
+----------------+
| current_user() |
+----------------+
| ggyy@localhost |
+----------------+
1 row in set (0.00 sec)
mysql> show databases;
+--------------------+
| Database |
+--------------------+
| information_schema |
| ggyy |
+--------------------+
2 rows in set (0.00 sec)
mysql> use ggyy
Database changed
mysql> show tables;
+----------------+
| Tables_in_ggyy |
+----------------+
| blob_text_test |
| char_test |
| contact |
| date_time_test |
| float_test |
| groups1 |
| groups2 |
| int_test |
| members |
| members_temp |
| processes1 |
| test_crttb |
| test_crttb2 |
| test_crttb3 |
| test_crttb4 |
| test_crttb5 |
| ts_dt_test |
| users1 |
+----------------+
18 rows in set (0.00 sec)
mysql> select * from groups1 limit 1;
+------+-------+
| gid | gname |
+------+-------+
| 0 | root |
+------+-------+
1 row in set (0.00 sec)
mysql> insert into groups1 values (255, 'test');
ERROR 1142 (42000): INSERT command denied to user 'ggyy'@'localhost' for table 'groups1'
mysql> delete from groups1 where gname = 'root';
ERROR 1142 (42000): DELETE command denied to user 'ggyy'@'localhost' for table 'groups1'
db表中的權(quán)限列相當(dāng)于“總開(kāi)關(guān)”,host表中的權(quán)限列相當(dāng)于“分開(kāi)關(guān)”,只有兩個(gè)“開(kāi)關(guān)”都打開(kāi)了,用戶才擁有相應(yīng)操作的權(quán)限。
mysql> select current_user();
+----------------+
| current_user() |
+----------------+
| root@localhost |
+----------------+
1 row in set (0.00 sec)
mysql> update mysql.db set insert_priv = 'Y' where db = 'ggyy';
Query OK, 1 row affected (0.00 sec)
Rows matched: 1 Changed: 1 Warnings: 0
mysql> update mysql.host set delete_priv = 'Y' where db = 'ggyy';
Query OK, 1 row affected (0.00 sec)
Rows matched: 1 Changed: 1 Warnings: 0
mysql> select host, db, user, select_priv, insert_priv, delete_priv from mysql.db where db = 'ggyy';
+------+------+------+-------------+-------------+-------------+
| host | db | user | select_priv | insert_priv | delete_priv |
+------+------+------+-------------+-------------+-------------+
| | ggyy | ggyy | Y | Y | Y |
+------+------+------+-------------+-------------+-------------+
1 row in set (0.00 sec)
mysql> select host, db, select_priv, insert_priv, delete_priv from mysql.host where db = 'ggyy';
+-----------+------+-------------+-------------+-------------+
| host | db | select_priv | insert_priv | delete_priv |
+-----------+------+-------------+-------------+-------------+
| localhost | ggyy | Y | Y | Y |
+-----------+------+-------------+-------------+-------------+
1 row in set (0.00 sec)
mysql> flush privileges;
Query OK, 0 rows affected (0.00 sec)
再次使用ggyy用戶嘗試插入和刪除操作:
mysql> select current_user();
+----------------+
| current_user() |
+----------------+
| ggyy@localhost |
+----------------+
1 row in set (0.00 sec)
mysql> insert into groups1 values (255, 'test');
Query OK, 1 row affected (0.00 sec)
mysql> delete from groups1 where gname = 'root';
Query OK, 1 rows affected (0.00 sec)
這種由db表和host表一起確定的權(quán)限,使用SHOW GRANTS命令看不到,也無(wú)法使用REVOKE命令回收。
mysql> select current_user();
+----------------+
| current_user() |
+----------------+
| root@localhost |
+----------------+
1 row in set (0.00 sec)
mysql> show grants for ggyy@localhost;
+-------------------------------------------------------------------------------------------------------------+
| Grants for ggyy@localhost |
+-------------------------------------------------------------------------------------------------------------+
| GRANT USAGE ON *.* TO 'ggyy'@'localhost' IDENTIFIED BY PASSWORD '*484FFAA42C12F40931C794D33A11B7F075B91467' |
+-------------------------------------------------------------------------------------------------------------+
1 row in set (0.00 sec)
mysql> revoke select on ggyy.* from ggyy@localhost;
ERROR 1141 (42000): There is no such grant defined for user 'ggyy' on host 'localhost'
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