public static class SocketExtensions

    {

        //found at http://www.extensionmethod.net/Details.aspx?ID=271, slightly modified

        /// <summary>

        /// Using IOControl code to configue socket KeepAliveValues for line disconnection detection(because default is toooo slow) 

        /// </summary>

        /// <param name="instance">A socket instance</param>

        /// <param name="KeepAliveTime">The keep alive time. (ms)</param>

        /// <param name="KeepAliveInterval">The keep alive interval. (ms)</param>

        public static void SetSocketKeepAliveValues(this Socket instance, int KeepAliveTime, int KeepAliveInterval)

        {

            //KeepAliveTime: default value is 2hr

            //KeepAliveInterval: default value is 1s and Detect 5 times



            //the native structure

            //struct tcp_keepalive {

            //ULONG onoff;

            //ULONG keepalivetime;

            //ULONG keepaliveinterval;

            //};



            uint dummy = 0; //lenth = 4

            int length = Marshal.SizeOf(dummy);

            byte[] inOptionValues = new byte[length * 3]; //size = lenth * 3 = 12

            bool OnOff = true;



            BitConverter.GetBytes((uint)(OnOff ? 1 : 0)).CopyTo(inOptionValues, 0);

            BitConverter.GetBytes((uint)KeepAliveTime).CopyTo(inOptionValues, length);

            BitConverter.GetBytes((uint)KeepAliveInterval).CopyTo(inOptionValues, length * 2);

            // of course there are other ways to marshal up this byte array, this is just one way