作者:Sri Sakthivel
原文链接:https://www.percona.com/blog/enhanced-password-management-systems-in-mysql-8-part-1
MySQL 8.0 在密码管理方面有很多改善,本文将介绍以下两个特性。
- 密码重用策略
- 生成随机密码
| 1 密码重用策略
该策略简单说,就是设置新密码时,可以限制禁止使用曾经用过的密码。有以下两种策略:
- 历史密码 password_history
- 间隔时间 password_reuse_interval
1.1 历史密码
MySQL 官方手册描述:
If an account is restricted on the basis of number of password changes, a new password cannot be chosen from a specified number of the most recent passwords.
在实验环境中,创建用户并添加条件password history 2
,历史密码中最近的两个不能被重新使用。
mysql> create user 'herc'@'localhost' identified by 'Percona@321' password history 2; Query OK, 0 rows affected (0.02 sec) mysql> select user, host, password_reuse_history from mysql.user where user='herc'\G *************************** 1. row *************************** user: herc host: localhost password_reuse_history: 2 1 row in set (0.00 sec)
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MySQL 将在 mysql.password_history
表上记录密码更改的信息。
mysql> select * from mysql.password_history; +-----------+------+----------------------------+------------------------------------------------------------------------+ | Host | User | Password_timestamp | Password | +-----------+------+----------------------------+------------------------------------------------------------------------+ | localhost | herc | 2021-09-20 15:44:42.295778 | $A$005$=R:q'M(Kh#D];c~SdCLyluq2UVHFobjWOFTwn2JYVFDyI042sl56B7DCPSK5 | +-----------+------+----------------------------+------------------------------------------------------------------------+ 1 row in set (0.00 sec)
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接下来我们尝试更改用户 herc@localhost
的密码。
mysql> alter user 'herc'@'localhost' identified by 'MySQL@321'; Query OK, 0 rows affected (0.02 sec) mysql> select * from mysql.password_history\G *************************** 1. row *************************** Host: localhost User: herc Password_timestamp: 2021-09-20 15:49:15.459018 CGeRQT31UUwtw194KOKGdNbgj3558VUB.dxcoS8r4IKpG8 *************************** 2. row *************************** Host: localhost User: herc Password_timestamp: 2021-09-20 15:44:42.295778 Password: $A$005$=R:q'M(Kh#D];c~SdCLyluq2UVHFobjWOFTwn2JYVFDyI042sl56B7DCPSK5 2 rows in set (0.00 sec)
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更改成功后,查看 mysql.password_history
表,可见该表存有最近两个密码的信息。
再次更改该用户密码,且密码为创建用户时设置的密码值(Percona@321)。
mysql> alter user 'herc'@'localhost' identified by 'Percona@321'; ERROR 3638 (HY000): Cannot use these credentials for 'herc@localhost' because they contradict the password history policy
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修改失败! 因为根据我们设置的限制策略,不能重用在 mysql.password_policy
表中被记录的最近的两个密码。因此,如果想再次重复使用第一个密码,就不能让该密码出现在 mysql.password_policy
表中。
再设置一个新密码后(第一个密码已经不是最近的两个密码了),再尝试用第一个密码值(Percona@321)进行修改,修改成功!
mysql> alter user 'herc'@'localhost' identified by 'Herc@321'; Query OK, 0 rows affected (0.01 sec) mysql> alter user 'herc'@'localhost' identified by 'Percona@321'; Query OK, 0 rows affected (0.02 sec)
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也可以在启动时在全局配置 password_history
。
#vi my.cnf [mysqld] password_history=6 #set global mysql> set global password_history=5; Query OK, 0 rows affected (0.00 sec)
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1.2 间隔时间
MySQL 官方手册描述:
If an account is restricted based on time elapsed, a new password cannot be chosen from passwords in the history that are newer than a specified number of days.
测试前,创建了用户 sri@localhost
,并设置用户密码可重用的时间间隔为五天。
mysql> create user 'sri'@'localhost' identified by 'Percona@321' password reuse interval 5 day; Query OK, 0 rows affected (0.01 sec) mysql> select user, host, password_reuse_time from mysql.user where user='sri'\G *************************** 1. row *************************** user: sri host: localhost password_reuse_time: 5 1 row in set (0.00 sec)
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这意味着每个密码生效后,在五天内都不能再被重复设置。
mysql> select * from mysql.password_history where user='sri'\G *************************** 1. row *************************** Host: localhost User: sri Password_timestamp: 2021-09-20 16:09:27.918585 Password: $A$005$+B e3!C9&8m eFRG~IqRWX4b6PtzLA8I4VsdYvWU3qRs/nip/QRhXXR5phT6 1 row in set (0.00 sec)
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执行 ALTER 来更改密码。
mysql> alter user 'sri'@'localhost' identified by 'Herc@321'; Query OK, 0 rows affected (0.02 sec) mysql> select * from mysql.password_history where user='sri'\G *************************** 1. row *************************** Host: localhost User: sri Password_timestamp: 2021-09-20 16:17:51.840483 Password: $A$005$~k7qp8.OP=^#e79qwtiYd7/cmCFLvHM7MHFbvfX2WlhXqzjmrN03gGZ4 *************************** 2. row *************************** Host: localhost User: sri Password_timestamp: 2021-09-20 16:09:27.918585 Password: $A$005$+B e3!C9&8m eFRG~IqRWX4b6PtzLA8I4VsdYvWU3qRs/nip/QRhXXR5phT6 2 rows in set (0.00 sec)
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现在尝试再次设置为第一个密码。
mysql> alter user 'sri'@'localhost' identified by 'Percona@321'; ERROR 3638 (HY000): Cannot use these credentials for 'sri@localhost' because they contradict the password history policy
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设置失败!
也可以在启动时在全局配置 password_reuse_interval
。
#vi my.cnf [mysqld] password_reuse_interval=365 #set global mysql> set global password_reuse_interval=365; Query OK, 0 rows affected (0.00 sec)
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| 2 随机密码
从 MySQL 8.0.18 开始,MySQL 能够为用户帐户创建随机密码。这意味着可以不必分配指定密码。它支持以下语句:
- 创建用户
- 更改用户
- 设置密码
我们需要使用 RANDOM PASSWORD
以避免修改密码时屏幕上有明文显示。例如:
mysql> create user 'sakthi'@'localhost' identified by random password; +--------+-----------+----------------------+ | user | host | generated password | +--------+-----------+----------------------+ | sakthi | localhost | .vZYy+<<BO7l1;vtIufH | +--------+-----------+----------------------+ 1 row in set (0.01 sec) mysql> alter user 'sri'@'localhost' identified by random password; +------+-----------+----------------------+ | user | host | generated password | +------+-----------+----------------------+ | sri | localhost | 5wb>2[]q*jbDsFvlN-i_ | +------+-----------+----------------------+ 1 row in set (0.02 sec)
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密码哈希值将存储在 mysql.user
表中。
mysql> select user, authentication_string from mysql.user where user in ('sakthi','sri')\G *************************** 1. row *************************** user: sakthi authentication_string: $A$005$L`PYcedj%3tz*J>ioBP1.Rsrj7H8wtelqijvV0CFnXVnWLNIc/RZL0C06l4oA *************************** 2. row *************************** user: sri authentication_string: $A$005$/k?aO&ap.#b= ^zt[E|x9q3w9uHn1oEumXUgnqNMH8xWo4xd/s26hTPKs1AbC2 2 rows in set (0.00 sec)
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默认情况下,密码长度为 20 个字符。我们可以使用变量 generated_random_password_length
定义密码长度,允许的长度范围是 5 到 255。
mysql> select @@generated_random_password_length; +------------------------------------+ | @@generated_random_password_length | +------------------------------------+ | 20 | +------------------------------------+ 1 row in set (0.00 sec)
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如果 validate_password
组件已经安装,对随机密码策略不会有影响。
还有一些特性,将在下一篇文章中介绍。
参考
MySQL 手册:
-
https://dev.mysql.com/doc/mysql-security-excerpt/8.0/en/password-management.html
-
https://dev.mysql.com/doc/refman/8.0/en/password-management.html#random-password-generation