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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: 03.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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