连接MySQL报错，is not allowed to connect to this MySQL server

问题描述：

        本机装的MySQL数据库，本机可以正常连接，其他机器访问报错，is not allowed to connect to this MySQL server，防火墙等其他策略均配置没问题。

---

 解决方案：

        出现该问题的原因是，MySQL数据库只允许自身所在的本机器连接，不允许远程连接。

1、在MySQL所在服务器上使用命令登录到MySQL数据库中

mysql -u root -p

2、选择mysql数据库，并查询权限

use mysql;
 
select host from user where user='root';

可以看到，执行查询语句后得到的数据结果中 host 的值是 localhost

我们执行update语句修改权限

update user set host = '%' where user ='root';

3、刷新配置

flush privileges;

再次执行查询权限语句

select host from user where user='root';

可以看到，已经修改成功

4、最后再次用其他机器连接MySQL数据库，可以连接成功

DBMS: MySQL (版本 5.7.41)
区分大小写: 普通形式=lower, 分隔形式=lower
驱动程序: MySQL Connector/J (版本 mysql-connector-java-8.0.25 (Revision: 08be9e9b4cba6aa115f9b27b215887af40b159e0)，JDBC4.2)

Ping: 29毫秒
SSL: yes

---

<?xml version="1.0" encoding="UTF-8"?>
 
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 |  1. User Level. This settings.xml file provides configuration for a single user,
 |                 and is normally provided in ${user.home}/.m2/settings.xml.
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 |                 NOTE: This location can be overridden with the CLI option:
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 |                 -s /path/to/user/settings.xml
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 |  2. Global Level. This settings.xml file provides configuration for all Maven
 |                 users on a machine (assuming they're all using the same Maven
 |                 installation). It's normally provided in
 |                 ${maven.conf}/settings.xml.
 |
 |                 NOTE: This location can be overridden with the CLI option:
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 |                 -gs /path/to/global/settings.xml
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 | The sections in this sample file are intended to give you a running start at
 | getting the most out of your Maven installation. Where appropriate, the default
 | values (values used when the setting is not specified) are provided.
 |
 |-->
<settings xmlns="http://maven.apache.org/SETTINGS/1.2.0"
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  <!-- interactiveMode
   | This will determine whether maven prompts you when it needs input. If set to false,
   | maven will use a sensible default value, perhaps based on some other setting, for
   | the parameter in question.
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   | Default: true
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  <!-- offline
   | Determines whether maven should attempt to connect to the network when executing a build.
   | This will have an effect on artifact downloads, artifact deployment, and others.
   |
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  <!-- pluginGroups
   | This is a list of additional group identifiers that will be searched when resolving plugins by their prefix, i.e.
   | when invoking a command line like "mvn prefix:goal". Maven will automatically add the group identifiers
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  <pluginGroups>
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     | Specifies a further group identifier to use for plugin lookup.
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  </pluginGroups>
 
  <!-- proxies
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   | Unless otherwise specified (by system property or command-line switch), the first proxy
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  <proxies>
    <!-- proxy
     | Specification for one proxy, to be used in connecting to the network.
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      <username>proxyuser</username>
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      <host>proxy.host.net</host>
      <port>80</port>
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  <!-- servers
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    <!-- server
     | Specifies the authentication information to use when connecting to a particular server, identified by
     | a unique name within the system (referred to by the 'id' attribute below).
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     | NOTE: You should either specify username/password OR privateKey/passphrase, since these pairings are
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     |
    <server>
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  <!-- profiles
   | This is a list of profiles which can be activated in a variety of ways, and which can modify
   | the build process. Profiles provided in the settings.xml are intended to provide local machine-
   | specific paths and repository locations which allow the build to work in the local environment.
   |
   | For example, if you have an integration testing plugin - like cactus - that needs to know where
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   |
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   | relies on the detection of a system property, either matching a particular value for the property,
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  <profiles>
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     | Specifies a set of introductions to the build process, to be activated using one or more of the
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     | or the command line, profiles have to have an ID that is unique.
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     |   <artifactId>myplugin</artifactId>
     |
     |   <configuration>
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  <!-- activeProfiles
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1。 改表法。可能是你的帐号不允许从远程登陆，只能在localhost。这个时候只要在localhost的那台电脑，登入mysql后，更改 "mysql" 数据库里的 "user" 表里的 "host" 项，从"localhost"改称"%"

Sql代码 复制代码

   1. mysql -u root -pvmwaremysql>use mysql; 

   2. mysql>update user set host = '%' where user = 'root'; 

   3. mysql>select host, user from user; 

2. 授权法。例如，你想myuser使用mypassword从任何主机连接到mysql服务器的话。

Sql代码 复制代码

  1. GRANT ALL PRIVILEGES ON *.* TO 'myuser'@'%' IDENTIFIED BY 'mypassword' WITH

      GRANT OPTION;  

  2.FLUSH   PRIVILEGES;