使用Pomelo.EntityFrameworkCore.MySql v6跨设备连接MySQL失败问题

问题场景 #

本地机器使用Pomelo.EntityFrameworkCore.MySql v6连接MySQL数据库正常，但同一网络下的其他设备连接时报错，错误信息如下：

MySqlConnector.MySqlException (0x80004005): Unable to connect to any of the specified MySQL hosts.
   at MySqlConnector.Core.ServerSession.ConnectAsync(ConnectionSettings cs, MySqlConnection connection, Int32 startTickCount, ILoadBalancer loadBalancer, IOBehavior ioBehavior, CancellationToken cancellationToken) in /_/src/MySqlConnector/Core/ServerSession.cs:line 433
   at MySqlConnector.Core.ConnectionPool.ConnectSessionAsync(MySqlConnection connection, String logMessage, Int32 startTickCount, IOBehavior ioBehavior, CancellationToken cancellationToken) in /_/src/MySqlConnector/Core/ConnectionPool.cs:line 363
   at MySqlConnector.Core.ConnectionPool.GetSessionAsync(MySqlConnection connection, Int32 startTickCount, IOBehavior ioBehavior, CancellationToken cancellationToken) in /_/src/MySqlConnector/Core/ConnectionPool.cs:line 94
   at MySqlConnector.Core.ConnectionPool.GetSessionAsync(MySqlConnection connection, Int32 startTickCount, IOBehavior ioBehavior, CancellationToken cancellationToken) in /_/src/MySqlConnector/Core/ConnectionPool.cs:line 124
   at MySqlConnector.MySqlConnection.CreateSessionAsync(ConnectionPool pool, Int32 startTickCount, Nullable`1 ioBehavior, CancellationToken cancellationToken) in /_/src/MySqlConnector/MySqlConnection.cs:line 915
   at MySqlConnector.MySqlConnection.OpenAsync(Nullable`1 ioBehavior, CancellationToken cancellationToken) in /_/src/MySqlConnector/MySqlConnection.cs:line 406
   at MySqlConnector.MySqlConnection.Open() in /_/src/MySqlConnector/MySqlConnection.cs:line 369
   at Microsoft.EntityFrameworkCore.ServerVersion.AutoDetect(String connectionString)
   at MadaSoft.AddDbContextHostBuilderExtensions.<>c__DisplayClass1_0.<GetMySql>b__0(DbContextOptionsBuilder o) in D:\VS Projects\MadaProject\MadaSoft\HostBuilder\AddDbContextHostBuilderExtensions.cs:line 32
   at MadaSoft.ContextFactoryApp.CreateDbContext() in D:\VS Projects\MadaProject\MadaSoft\_DbContext\ContextFactoryApp.cs:line 19
   at MadaSoft.App.MigrateContextApp() in D:\VS Projects\MadaProject\MadaSoft\App.xaml.cs:line 63
   at MadaSoft.App.OnStartupTask() in D:\VS Projects\MadaProject\MadaSoft\App.xaml.cs:line 55
   at MadaSoft.App.OnStartup(StartupEventArgs e) in D:\VS Projects\MadaProject\MadaSoft\App.xaml.cs:line 35

服务注册代码：

Action<DbContextOptionsBuilder> configureDbContext = o =>
{
    o.UseMySql(connectionString, ServerVersion.AutoDetect(connectionString));
    o.UseQueryTrackingBehavior(QueryTrackingBehavior.NoTracking);
}; 

services.AddDbContext<ContextApp>(configureDbContext);
services.AddSingleton(new ContextFactoryApp(configureDbContext));

使用的连接字符串：
server=localhost; Port=3306; Database=dbName; Uid=root; Pwd=root; sslmode=none; CharSet=utf8;

排查步骤 #

1. 修正连接字符串的服务器地址 #

当前连接字符串中server=localhost仅指向本地回环地址，其他设备无法解析到数据库服务器。需替换为数据库所在机器的局域网IP地址（如192.168.1.100）：

server=192.168.x.x; Port=3306; Database=dbName; Uid=root; Pwd=root; sslmode=none; CharSet=utf8;

2. 检查MySQL服务的IP绑定设置 #

MySQL默认可能仅绑定127.0.0.1，限制本地访问：

• 找到MySQL配置文件（Windows为my.ini，Linux为my.cnf）
• 修改bind-address参数为0.0.0.0（允许所有IP访问），或指定具体的局域网IP段
• 修改后重启MySQL服务生效

3. 授权数据库用户的跨IP访问权限 #

当前root用户可能仅允许本地登录，需授权其从其他IP访问：

-- 允许root从任意IP访问指定数据库
GRANT ALL PRIVILEGES ON dbName.* TO 'root'@'%' IDENTIFIED BY 'root';
-- 刷新权限使设置生效
FLUSH PRIVILEGES;

注：%表示允许所有IP，也可指定具体IP（如192.168.%.%）提升安全性

4. 排查防火墙/安全软件拦截 #

• 数据库所在机器的防火墙需开放3306端口，添加允许同网络设备访问的入站规则
• 临时关闭杀毒软件、安全防护工具，测试是否能正常连接，排除软件拦截问题

5. 验证网络连通性 #

在客户端设备上执行以下命令：

• 测试服务器IP可达性：ping 192.168.x.x
• 测试3306端口开放状态：telnet 192.168.x.x 3306 或 nc -zv 192.168.x.x 3306
• 确认客户端与服务器处于同一局域网，无VLAN隔离等网络限制

内容的提问来源于stack exchange，提问作者eng_hr.ye