mysql 8.0 用戶修改爲簡單密碼

os: centos 7.4
db: mysql 8.0.19

版本

# cat /etc/centos-release
CentOS Linux release 7.4.1708 (Core) 
#
# mysql -h localhost -u root -p
Enter password: 
Welcome to the MySQL monitor.  Commands end with ; or \g.
Your MySQL connection id is 9
Server version: 8.0.19

Copyright (c) 2000, 2020, Oracle and/or its affiliates. All rights reserved.

Oracle is a registered trademark of Oracle Corporation and/or its
affiliates. Other names may be trademarks of their respective
owners.

Type 'help;' or '\h' for help. Type '\c' to clear the current input statement.

mysql> select version();
+-----------+
| version() |
+-----------+
| 8.0.19    |
+-----------+
1 row in set (0.00 sec)

mysql> 

alter user identified by

使用 yum 安裝 mysql-server 後，第一次啓動 mysql ，會自動創建一個 mysql 數據庫

# systemctl start mysqld.server

默認生成的 ‘root’@‘localhost’ 密碼保存在 /var/log/mysqld.log

# cat /var/log/mysqld.log 
2020-02-25T13:43:20.116141Z 0 [System] [MY-013169] [Server] /usr/sbin/mysqld (mysqld 8.0.19) initializing of server in progress as process 5195
2020-02-25T13:43:24.206701Z 5 [Note] [MY-010454] [Server] A temporary password is generated for root@localhost: 8t89OsTdEs,&
2020-02-25T13:43:29.311452Z 0 [System] [MY-010116] [Server] /usr/sbin/mysqld (mysqld 8.0.19) starting as process 5246
2020-02-25T13:43:30.001833Z 0 [Warning] [MY-010068] [Server] CA certificate ca.pem is self signed.
2020-02-25T13:43:30.063997Z 0 [System] [MY-010931] [Server] /usr/sbin/mysqld: ready for connections. Version: '8.0.19'  socket: '/var/lib/mysql/mysql.sock'  port: 3306  MySQL Community Server - GPL.
2020-02-25T13:43:30.286359Z 0 [System] [MY-011323] [Server] X Plugin ready for connections. Socket: '/var/run/mysqld/mysqlx.sock' bind-address: '0.0.0.0' port: 33060

登錄後，需要第一時間修改密碼，但是如果是測試庫的話，密碼沒必要設置的很複雜，就需要修改一下

# mysql -h localhost -u root -p
Enter password: 

mysql> select * from mysql.user;
ERROR 1820 (HY000): You must reset your password using ALTER USER statement before executing this statement.
mysql> alter user 'root'@'localhost' identified by 'mysqlmysql';
ERROR 1819 (HY000): Your password does not satisfy the current policy requirements
mysql> 

先臨時修改一個較複雜的密碼

mysql> alter user 'root'@'localhost' identified by 'PAss@@2020';
Query OK, 0 rows affected (0.22 sec)

mysql 8.0 的密碼默認使用 caching_sha2_password ，已不再是 mysql_native_password 。

mysql> show global variables like '%default_auth%';
+-------------------------------+-----------------------+
| Variable_name                 | Value                 |
+-------------------------------+-----------------------+
| default_authentication_plugin | caching_sha2_password |
+-------------------------------+-----------------------+
1 row in set (0.00 sec)

validate_password 相關參數，看上去 8.0 相比 5.7 改成了"."

mysql> show global variables like 'validate_password%';
+--------------------------------------+--------+
| Variable_name                        | Value  |
+--------------------------------------+--------+
| validate_password.check_user_name    | ON     |
| validate_password.dictionary_file    |        |
| validate_password.length             | 8      |
| validate_password.mixed_case_count   | 1      |
| validate_password.number_count       | 1      |
| validate_password.policy             | MEDIUM |
| validate_password.special_char_count | 1      |
+--------------------------------------+--------+
7 rows in set (0.00 sec)

臨時修改 validate_password 參數

mysql> set global validate_password.policy=0;
mysql> set global validate_password.length=4;

mysql> alter user 'root'@'localhost' identified by 'mysqlmysql';
Query OK, 0 rows affected (0.01 sec)

mysql> select host,user,plugin,authentication_string from mysql.user;
+-----------+------------------+-----------------------+------------------------------------------------------------------------+
| host      | user             | plugin                | authentication_string                                                  |
+-----------+------------------+-----------------------+------------------------------------------------------------------------+
| localhost | mysql.infoschema | caching_sha2_password | $A$005$THISISACOMBINATIONOFINVALIDSALTANDPASSWORDTHATMUSTNEVERBRBEUSED |
| localhost | mysql.session    | caching_sha2_password | $A$005$THISISACOMBINATIONOFINVALIDSALTANDPASSWORDTHATMUSTNEVERBRBEUSED |
| localhost | mysql.sys        | caching_sha2_password | $A$005$THISISACOMBINATIONOFINVALIDSALTANDPASSWORDTHATMUSTNEVERBRBEUSED |
| localhost | root             | caching_sha2_password | $A$005$3
                                                                 -b%<1x}8Neyo`@vGfGUUFglFEZnzdOcz5ev/Z.oUKTH34s7EH0VZdBKH43 |
+-----------+------------------+-----------------------+------------------------------------------------------------------------+
4 rows in set (0.00 sec)

永久修改的話，需要修改 my.cnf 參數文件

# vi /etc/my.cnf

validate_password.policy=0
validate_password.length=4
validate_password.number_count=0
validate_password.mixed_case_count=0
validate_password.special_char_count=0

如果使用 mysql_native_password 方式請參考
<<mysql 8.0 的用戶認證方式 caching_sha2_password、mysql_native_password>>
<<mysql 密碼插件 validate_password>>

參考：