之前项目在测试服务器上的一些接口时不时会报出下面的错误：（采用Abp框架）
"SocketException: 你的主机中的软件中止了一个已建立的连接。 STACK TRACE: at MySqlConnector.Protocol.Serialization.SocketByteHandler.WriteBytesAsync(ArraySegment`1 data, IOBehavior ioBehavior) in C:\projects\mysqlconnector\src\MySqlConnector\Protocol\Serialization\SocketByteHandler.cs:line 90 --- End of stack trace from previous location where exception was thrown --- at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw() at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task) at MySqlConnector.Utilities.ValueTaskExtensions.<ContinueWith>d__0`2.MoveNext() in C:\projects\mysqlconnector\src\MySqlConnector\Utilities\ValueTaskExtensions.cs:line 8 --- End of stack trace from previous location where exception was thrown --- at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw() at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task) at MySqlConnector.Core.ServerSession.TryAsyncContinuation(Task`1 task) in C:\projects\mysqlconnector\src\MySqlConnector\Core\ServerSession.cs:line 1225 at System.Threading.Tasks.ContinuationResultTaskFromResultTask`2.InnerInvoke() at System.Threading.ExecutionContext.Run(ExecutionContext executionContext, ContextCallback callback, Object state) at System.Threading.Tasks.Task.ExecuteWithThreadLocal(Task& currentTaskSlot) --- End of stack trace from previous location where exception was thrown --- at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw() at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task) at MySqlConnector.Core.TextCommandExecutor.<ExecuteReaderAsync>d__1.MoveNext() in C:\projects\mysqlconnector\src\MySqlConnector\Core\TextCommandExecutor.cs:line 36 --- End of stack trace from previous location where exception was thrown --- at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw() at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task) at MySql.Data.MySqlClient.MySqlCommand.<ExecuteNonQueryAsync>d__60.MoveNext() in C:\projects\mysqlconnector\src\MySqlConnector\MySql.Data.MySqlClient\MySqlCommand.cs:line 261 --- End of stack trace from previous location where exception was thrown --- at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw() at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task) at MySql.Data.MySqlClient.MySqlCommand.ExecuteNonQuery() in C:\projects\mysqlconnector\src\MySqlConnector\MySql.Data.MySqlClient\MySqlCommand.cs:line 62 at MySql.Data.MySqlClient.MySqlTransaction.Dispose(Boolean disposing) in C:\projects\mysqlconnector\src\MySqlConnector\MySql.Data.MySqlClient\MySqlTransaction.cs:line 81 at Microsoft.EntityFrameworkCore.Storage.RelationalTransaction.Dispose() at Abp.EntityFrameworkCore.Uow.DbContextEfCoreTransactionStrategy.Dispose(IIocResolver iocResolver) at Abp.EntityFrameworkCore.Uow.EfCoreUnitOfWork.DisposeUow() at Abp.Domain.Uow.UnitOfWorkBase.Dispose() at Abp.AspNetCore.Mvc.Uow.AbpUowActionFilter.<OnActionExecutionAsync>d__4.MoveNext() --- End of stack trace from previous location where exception was thrown --- at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw() at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task) at Microsoft.AspNetCore.Mvc.Internal.ControllerActionInvoker.<InvokeNextActionFilterAsync>d__10.MoveNext() --- End of stack trace from previous location where exception was thrown --- at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw() at Microsoft.AspNetCore.Mvc.Internal.ControllerActionInvoker.Rethrow(ActionExecutedContext context) at Microsoft.AspNetCore.Mvc.Internal.ControllerActionInvoker.Next(State& next, Scope& scope, Object& state, Boolean& isCompleted) at Microsoft.AspNetCore.Mvc.Internal.ControllerActionInvoker.<InvokeInnerFilterAsync>d__13.MoveNext() --- End of stack trace from previous location where exception was thrown --- at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw() at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task) at Microsoft.AspNetCore.Mvc.Internal.ResourceInvoker.<InvokeNextExceptionFilterAsync>d__24.MoveNext() "View Code
MySql.Data.MySqlClient.MySqlException (0x80004005): Failed to read the result set. ---> System.IO.EndOfStreamException: Expected to read 4 header bytes but only received 0. at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw() at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task) at MySqlConnector.Protocol.Serialization.ProtocolUtility.DoReadPayloadAsync(BufferedByteReader bufferedByteReader, IByteHandler byteHandler, Func`1 getNextSequenceNumber, ArraySegmentHolder`1 previousPayloads, ProtocolErrorBehavior protocolErrorBehavior, IOBehavior ioBehavior) in C:\projects\mysqlconnector\src\MySqlConnector\Protocol\Serialization\ProtocolUtility.cs:line 462 at MySqlConnector.Protocol.Serialization.StandardPayloadHandler.ReadPayloadAsync(ArraySegmentHolder`1 cache, ProtocolErrorBehavior protocolErrorBehavior, IOBehavior ioBehavior) in C:\projects\mysqlconnector\src\MySqlConnector\Protocol\Serialization\StandardPayloadHandler.cs:line 37 at MySqlConnector.Core.ServerSession.ReceiveReplyAsync(IOBehavior ioBehavior, CancellationToken cancellationToken) in C:\projects\mysqlconnector\src\MySqlConnector\Core\ServerSession.cs:line 645 --- End of stack trace from previous location where exception was thrown --- at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw() at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task) at MySqlConnector.Core.ServerSession.TryAsyncContinuation(Task`1 task) in C:\projects\mysqlconnector\src\MySqlConnector\Core\ServerSession.cs:line 1230 at System.Threading.Tasks.ContinuationResultTaskFromResultTask`2.InnerInvoke() at System.Threading.ExecutionContext.Run(ExecutionContext executionContext, ContextCallback callback, Object state) at System.Threading.Tasks.Task.ExecuteWithThreadLocal(Task& currentTaskSlot) --- End of stack trace from previous location where exception was thrown ---View Code
然后我使用swagger+miniprofiler，查看生成的sql语句
查看Mysql错误日志：
Aborted connection 422 to db: '数据库名称' user: 'root' host: 'localhost' (Got a packet bigger than 'max_allowed_packet' bytes)
可能因为传输的数据过大，而Mysql的max_allowed_packet默认为1024b，导致sql执行不成功。
然后将Mysql配置文件中的max_allowed_packet值改为max_allowed_packet = 4M
重启Mysql，问题解决。
然而过了一段时间，同样的报错又出现了，首先看了下max_allowed_packet的值，果然max_allowed_packet又被修改为了1024b，查看命令如下：
show variables like '%max_allowed_packet%';
然后询问同事，他们说并没有动数据库，上网查了下说是有可能是被攻击了。
于是我开启了Mysql的日志，命令如下：
set global general_log=on;
在日志里看到了被修改信息，然后看了下ip~~~
还发现了几个新增用户TvT，把它删掉：
查看Mysql用户命令如下：
select * from mysql.user
目前解决方法是，加强密码，限制远程连接ip：把上图的% 改为指定ip段xxx.xxx.xxx.%，重启Mysql。