socket通信的KeepAlive默认时间是2小时，通过以下代码可以改变其时间，来检测socket通信过程中自网线，服务器网线断等事件

#include

#include "winsock2.h"

#include

#include

#pragma comment(lib, "Ws2_32.lib")

#include

#include "MSTcpIp.h"

using namespace std;

const int BUF_LEN = 1024;

class CDataSocket : public CAsyncSocket

{

public:

void OnConnect(int nErrorCode)

{

}

void OnReceive(int nErrorCode)

{

BYTE byBuf[BUF_LEN + 1];

int nRecv = Receive(byBuf, BUF_LEN);

do

{

byBuf[nRecv] = '\0';

}while ((nRecv = Receive(byBuf, BUF_LEN)) == BUF_LEN);

}

void OnClose(int nErrorCode)

{

}

};

void main()

{

AfxWinInit(::GetModuleHandle(NULL), NULL, NULL, 0);

AfxSocketInit();

CAsyncSocket* psock = new CDataSocket;

psock->Create();

// KeepAlive

BOOL bOptVal = TRUE;

int bOptLen = sizeof(BOOL);

int iOptVal;

int iOptLen = sizeof(int);    if (getsockopt(psock->m_hSocket, SOL_SOCKET, SO_KEEPALIVE,

(char*)& iOptVal, & iOptLen) != SOCKET_ERROR) {

printf("SO_KEEPALIVE Value: %ld\n", iOptVal);

}

if (setsockopt(psock->m_hSocket, SOL_SOCKET, SO_KEEPALIVE,

(char*)& bOptVal, bOptLen) != SOCKET_ERROR) {

printf("Set SO_KEEPALIVE: ON\n");

}

if (getsockopt(psock->m_hSocket, SOL_SOCKET, SO_KEEPALIVE,

(char*)& iOptVal, & iOptLen) != SOCKET_ERROR) {

printf("SO_KEEPALIVE Value: %ld\n", iOptVal);

}

DWORD dwBytes,dwError = 0L ;

tcp_keepalive sKA_Settings = {0}, sReturned = {0} ;

sKA_Settings.onoff = 1 ;

sKA_Settings.keepalivetime = 20000 ; // Keep Alive

sKA_Settings.keepaliveinterval = 1000 ; // Resend if No-Reply

if (WSAIoctl(psock->m_hSocket, SIO_KEEPALIVE_VALS, & sKA_Settings,

sizeof(sKA_Settings), & sReturned, sizeof(sReturned), & dwBytes,

NULL, NULL) != 0)

{

dwError = WSAGetLastError() ;

return ;

}

psock->Connect(_T("XXX.XXX.XXX.XXX"), 5001);

}