//設置KeepAlive
BOOL bKeepAlive = TRUE;
nRet = ::setsockopt(m_sockDesc, SOL_SOCKET, SO_KEEPALIVE, (char*)&bKeepAlive, sizeof(bKeepAlive));
if (nRet !=0)
{
sprintf(m_pszError, "Winsock error : %s (Error Code %d)\n ", "Socket SetOpt failed ", WSAGetLastError());
return FALSE;
}

//設置KeepAlive檢測時間和次數
TCP_KEEPALIVE inKeepAlive = {0}; //輸入參數
unsigned long ulInLen = sizeof(TCP_KEEPALIVE);

TCP_KEEPALIVE outKeepAlive = {0}; //輸出參數
unsigned long ulOutLen = sizeof(TCP_KEEPALIVE);

unsigned long ulBytesReturn = 0;

//設置socket的keep alive為10秒，并且發送次數為3次
inKeepAlive.onoff = 1;
inKeepAlive.keepaliveinterval = 10000; //兩次KeepAlive探測間的時間間隔
inKeepAlive.keepalivetime = 3; //開始首次KeepAlive探測前的TCP空閉時間

nRet = WSAIoctl(m_sockDesc,
SIO_KEEPALIVE_VALS,
(LPVOID)&inKeepAlive,
ulInLen,
(LPVOID)&outKeepAlive,
ulOutLen,
&ulBytesReturn,
NULL,
NULL);
if(SOCKET_ERROR == nRet)
{
sprintf(m_pszError, "Winsock error : %s (Error Code %d)\n ", "Nonblocking socket call error ", WSAGetLastError());
return FALSE;
}

-------------------------------------------------------------------------------------------------------------------------------

//設置KeepAlive
BOOL bKeepAlive = TRUE;
nRet = ::setsockopt(m_sockDesc, SOL_SOCKET, SO_KEEPALIVE, (char*)&bKeepAlive, sizeof(bKeepAlive));
if (nRet !=0)
{
sprintf(m_pszError, "Winsock error : %s (Error Code %d)\n ", "Socket SetOpt failed ", WSAGetLastError());
return FALSE;
}

//設置KeepAlive檢測時間和次數
TCP_KEEPALIVE inKeepAlive = {0}; //輸入參數
unsigned long ulInLen = sizeof(TCP_KEEPALIVE);

TCP_KEEPALIVE outKeepAlive = {0}; //輸出參數
unsigned long ulOutLen = sizeof(TCP_KEEPALIVE);

unsigned long ulBytesReturn = 0;

//設置socket的keep alive為10秒，并且發送次數為3次
inKeepAlive.onoff = 1;
inKeepAlive.keepaliveinterval = 10000; //兩次KeepAlive探測間的時間間隔
inKeepAlive.keepalivetime = 3; //開始首次KeepAlive探測前的TCP空閉時間

nRet = WSAIoctl(m_sockDesc,
SIO_KEEPALIVE_VALS,
(LPVOID)&inKeepAlive,
ulInLen,
(LPVOID)&outKeepAlive,
ulOutLen,
&ulBytesReturn,
NULL,
NULL);
if(SOCKET_ERROR == nRet)
{
sprintf(m_pszError, "Winsock error : %s (Error Code %d)\n ", "Nonblocking socket call error ", WSAGetLastError());
return FALSE;
}