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引言
当我们在使用 MySQL 时#xff0c;可能遇到过如下类似的错误#xff1a;
Host IP is blocked because of many connection errors; unblock with mysqladmin flush-hosts该错误意味着 mysqld 已从给定主机收到许多中断的连接请求。并且数量超过…作者俊达
引言
当我们在使用 MySQL 时可能遇到过如下类似的错误
Host IP is blocked because of many connection errors; unblock with mysqladmin flush-hosts该错误意味着 mysqld 已从给定主机收到许多中断的连接请求。并且数量超过了max_connect_errors系统变量的值。
1 参数max_connect_errors
MySQL有参数max_connect_errors当一个主机尝试登录MySQL失败的次数超过了max_connect_errors则这个主机将无法登录到mysql。
下面是一个简单的测试
### max_connect_errors 设置成3
mysql show variables like %max_connect_errors%;
---------------------------
| Variable_name | Value |
---------------------------
| max_connect_errors | 100 |
---------------------------
1 row in set (0.00 sec)mysql set global max_connect_errors3;
Query OK, 0 rows affected (0.00 sec)mysql show variables like %max_connect_errors%;
---------------------------
| Variable_name | Value |
---------------------------
| max_connect_errors | 3 |
---------------------------### 模拟登陆失败访问3306端口
[rootbox1 ~]# telnet 172.16.20.51 3306
Trying 172.16.20.51...
Connected to 172.16.20.51.
Escape character is ^].
J
5.7.32QmIHUJd[103(Nmysql_native_password!#08S01Got packets out of orderConnection closed by foreign host.### 重试3次后无法登陆数据库
[rootbox1 ~]# telnet 172.16.20.51 3306
Trying 172.16.20.51...
Connected to 172.16.20.51.
Escape character is ^].
jHost 172.16.20.51 is blocked because of many connection errors; unblock with mysqladmin flush-hostsConnection closed by foreign host.#### 提供正确的密码也无法登录MySQL
[rootbox1 ~]# mysql -uauser -h172.16.20.51 -pauser
mysql: [Warning] Using a password on the command line interface can be insecure.
ERROR 1129 (HY000): Host 172.16.20.51 is blocked because of many connection errors; unblock with mysqladmin flush-hosts### 执行mysqladmin flush-hosts后可以登陆
[rootbox1 ecdsa]# mysqladmin -uroot -h127.0.0.1 -phello flush-hosts客户端连接错误信息记录在information_schema.host_cache表mysql服务端会从这个表读取数据获取主机登陆信息。mysqladmin flush-hosts的作用是清空这个表。
mysql select * from performance_schema.host_cache\G
*************************** 1. row ***************************IP: 172.16.20.51HOST: box1HOST_VALIDATED: YESSUM_CONNECT_ERRORS: 3COUNT_HOST_BLOCKED_ERRORS: 2COUNT_NAMEINFO_TRANSIENT_ERRORS: 0COUNT_NAMEINFO_PERMANENT_ERRORS: 0COUNT_FORMAT_ERRORS: 0COUNT_ADDRINFO_TRANSIENT_ERRORS: 0COUNT_ADDRINFO_PERMANENT_ERRORS: 0COUNT_FCRDNS_ERRORS: 0COUNT_HOST_ACL_ERRORS: 0COUNT_NO_AUTH_PLUGIN_ERRORS: 0COUNT_AUTH_PLUGIN_ERRORS: 0COUNT_HANDSHAKE_ERRORS: 5COUNT_PROXY_USER_ERRORS: 0COUNT_PROXY_USER_ACL_ERRORS: 0COUNT_AUTHENTICATION_ERRORS: 0COUNT_SSL_ERRORS: 0COUNT_MAX_USER_CONNECTIONS_ERRORS: 0
COUNT_MAX_USER_CONNECTIONS_PER_HOUR_ERRORS: 0COUNT_DEFAULT_DATABASE_ERRORS: 0COUNT_INIT_CONNECT_ERRORS: 0COUNT_LOCAL_ERRORS: 0COUNT_UNKNOWN_ERRORS: 0FIRST_SEEN: 2021-04-06 09:17:05LAST_SEEN: 2021-04-06 09:18:40FIRST_ERROR_SEEN: 2021-04-06 09:17:16LAST_ERROR_SEEN: 2021-04-06 09:18:40
1 row in set (0.00 sec)2 问题处理
1、验证链接 检查网络连接以确保您的主机不存在 TCP/IP 连接问题。 2、刷新缓存 mysqladmin flush-hosts命令清除缓存
[rootbox1 ecdsa] mysqladmin -uroot -h127.0.0.1 -phello flush-hosts3、调整max_connect_error参数 可以运行以下查询
mysql set global max_connect_errors10000;
Query OK, 0 rows affected (0.00 sec)3 总结
当一个主机连续登录mysql失败的次数超过max_connect_errors后将无法再次登录数据库。这些错误次数会按照主机的维度记录在performance_schema.host_cache表中。然而如果在一个主机达到max_connect_errors之前出现了一次成功的登录系统会将该主机的错误计数重置为0。为了重置错误次数我们可以使用mysqladmin flush-hosts命令。 针对运维的需求我们可以考虑适当调大max_connect_errors的值以提高系统的灵活性和容错性。通过调整这个参数我们可以更好地管理数据库的连接请求确保主机在尝试连接失败后仍有机会成功登录。这样我们可以更有效地进行运维管理确保数据库的稳定性和可靠性。
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