How to set the keep alive interval for winsock

Question

I am using winsock and TCP. I have set the KeepAlive option as follows

int aliveToggle = 1;
setsockopt(mySocket,SOL_SOCKET,SO_KEEPALIVE,(char*)&aliveToggle, sizeof(aliveToggle));

But how to specify the Keep aLive time and interval?

I am using VC++ running on windows 7.

Answer 1

Two per-interface registry settings under the key \HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Tcpip\Parameters control the behavior of TCP/IP keep-alives:

The KeepAliveTime value specifies how long the TCP connection sits idle, with no traffic, before TCP sends a keep-alive packet. The default is 7,200,000 milliseconds (ms) or 2 hours.

The KeepAliveInterval value indicates how many milliseconds to wait for a response after sending a keep-alive before repeating the keep-alive. If no response is received, the TCP/IP stack continues sending keep-alives at this interval until a response is received or until the stack reaches the packet retry limit specified in the TCPMaxDataRetransmissions registry key. KeepAliveInterval defaults to 1 second (1000 .

TCP keep-alives are disabled by default, but Windows Sockets applications can use the setsockopt function to enable them on a per-connection basis.

Note  If the developer elects to use TCP keep-alive messages on a particular connection, the timing of those messages is specified by the registry values described preceding. It is not possible to use different timing on different keep-alive requests.

Answer 2

From c/c++ you should be able to use SIO_KEEPALIVE_VALS to control the timeouts. You can't use setsockopt, but you should be able to use WSAIoctl. See https://web.archive.org/web/20130828175019/http://msdn.microsoft.com/en-us/library/windows/desktop/dd877220(v=vs.85).aspx

Here's an example https://web.archive.org/web/20130827074722/http://read.pudn.com/downloads79/ebook/301417/Chapter09/SIO_KEEPALIVE_VALS/alive.c__.htm