MySQL5.6.6版本之后增加了密碼強度驗證插件validate_password，相關參數設置的較為嚴格。
影響的語和函數有：create user,grant,set password,password(),old password。
1、查看mysql全局參數配置
mysql> SHOW VARIABLES LIKE 'validate_password%';
+--------------------------------------+--------+
| Variable_name | Value |
+--------------------------------------+--------+
| 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 |
+--------------------------------------+--------+
6 rows in set (0.08 sec)
2、參數解釋
validate_password_dictionary_file
插件用於驗證密碼強度的字典文件路徑。
validate_password_length
密碼最小長度，參數默認為8，它有最小值的限制，最小值為：validate_password_number_count + validate_password_special_char_count + (2 * validate_password_mixed_case_count)
validate_password_mixed_case_count
密碼至少要包含的小寫字母個數和大寫字母個數。
validate_password_number_count
密碼至少要包含的數字個數。
validate_password_policy
密碼強度檢查等級，0/LOW、1/MEDIUM、2/STRONG。有以下取值：
Policy Tests Performed
0 or LOW Length
1 or MEDIUM Length; numeric, lowercase/uppercase, and special characters
2 or STRONG Length; numeric, lowercase/uppercase, and special characters; dictionary file
默認是1，即MEDIUM，所以剛開始設置的密碼必須符合長度，且必須含有數字，小寫或大寫字母，特殊字符。
validate_password_special_char_count
密碼至少要包含的特殊字符數。
3、修改mysql參數配置
mysql> set global validate_password_policy=0;
Query OK, 0 rows affected (0.05 sec)
mysql> set global validate_password_mixed_case_count=0;
Query OK, 0 rows affected (0.00 sec)
mysql> set global validate_password_number_count=3;
Query OK, 0 rows affected (0.00 sec)
mysql> set global validate_password_special_char_count=0;
Query OK, 0 rows affected (0.00 sec)
mysql> set global validate_password_length=3;
Query OK, 0 rows affected (0.00 sec)
mysql> SHOW VARIABLES LIKE 'validate_password%';
+--------------------------------------+-------+
| Variable_name | Value |
+--------------------------------------+-------+
| validate_password_dictionary_file | |
| validate_password_length | 3 |
| validate_password_mixed_case_count | 0 |
| validate_password_number_count | 3 |
| validate_password_policy | LOW |
| validate_password_special_char_count | 0 |
+--------------------------------------+-------+
6 rows in set (0.00 sec)
(tip：MySQL8.0 以上版本改變如下：
+--------------------------------------+--------+
| 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 |
+--------------------------------------+--------+)
4、添加用戶且設置簡單的密碼
mysql> grant replication slave on *.* to 'replicate'@'127.0.0.1' identified by '123';
Query OK, 0 rows affected (0.01 sec)