public class NTPTimeHelper

    {

        /// <summary>

        /// 获取NTC时间

        /// </summary>

        /// <returns></returns>

        public static DateTime GetNetworkTime()

        {

            //default Windows time server

            string ntpServer = ConfigHelper.GetConfigToStr("NTPServer", "");

            // NTP message size - 16 bytes of the digest (RFC 2030)

            var ntpData = new byte[48];

            //Setting the Leap Indicator, Version Number and Mode values

            ntpData[0] = 0x1B; //LI = 0 (no warning), VN = 3 (IPv4 only), Mode = 3 (Client Mode)

            var addresses = Dns.GetHostEntry(ntpServer).AddressList;

            //The UDP port number assigned to NTP is 123

            var ipEndPoint = new IPEndPoint(addresses[0], 123);

            //NTP uses UDP

            var socket = new Socket(AddressFamily.InterNetwork, SocketType.Dgram, ProtocolType.Udp);

            socket.Connect(ipEndPoint);

            //Stops code hang if NTP is blocked

            socket.ReceiveTimeout = 3000;

            socket.Send(ntpData);

            socket.Receive(ntpData);

            socket.Close();

            //Offset to get to the "Transmit Timestamp" field (time at which the reply

            //departed the server for the client, in 64-bit timestamp format."

            const byte serverReplyTime = 40;

            //Get the seconds part

            ulong intPart = BitConverter.ToUInt32(ntpData, serverReplyTime);

            //Get the seconds fraction

            ulong fractPart = BitConverter.ToUInt32(ntpData, serverReplyTime + 4);

            //Convert From big-endian to little-endian

            intPart = SwapEndianness(intPart);

            fractPart = SwapEndianness(fractPart);

            var milliseconds = (intPart * 1000) + ((fractPart * 1000) / 0x100000000L);

            //**UTC** time

            var networkDateTime = (new DateTime(1900, 1, 1, 0, 0, 0, DateTimeKind.Utc)).AddMilliseconds((long)milliseconds);

            return networkDateTime.ToLocalTime();

        }

        // stackoverflow.com/a/3294698/162671

        static uint SwapEndianness(ulong x)

        {

            return (uint)(((x & 0x000000ff) << 24) +

            ((x & 0x0000ff00) << 8) +

            ((x & 0x00ff0000) >> 8) +

            ((x & 0xff000000) >> 24));

        }

    }

/// <summary>

    ///

    /// </summary>

    internal struct SYSTEMTIME

    {

        public ushort wYear;

        public ushort wMonth;

        public ushort wDayOfWeek;

        public ushort wDay;

        public ushort wHour;

        public ushort wMinute;

        public ushort wSecond;

        public ushort wMilliseconds;

        /// <summary>

        /// 从System.DateTime转换。

        /// </summary>

        /// <param name="time">System.DateTime类型的时间。</param>

        public void FromDateTime(DateTime time)

        {

            wYear = (ushort)time.Year;

            wMonth = (ushort)time.Month;

            wDayOfWeek = (ushort)time.DayOfWeek;

            wDay = (ushort)time.Day;

            wHour = (ushort)time.Hour;

            wMinute = (ushort)time.Minute;

            wSecond = (ushort)time.Second;

            wMilliseconds = (ushort)time.Millisecond;

        }

        /// <summary>

        /// 转换为System.DateTime类型。

        /// </summary>

        /// <returns></returns>

        public DateTime ToDateTime()

        {

            return new DateTime(wYear, wMonth, wDay, wHour, wMinute, wSecond, wMilliseconds);

        }

        /// <summary>

        /// 静态方法。转换为System.DateTime类型。

        /// </summary>

        /// <param name="time">SYSTEMTIME类型的时间。</param>

        /// <returns></returns>

        public static DateTime ToDateTime(SYSTEMTIME time)

        {

            return time.ToDateTime();

        }

    }

    internal class Win32API

    {

        [DllImport("Kernel32.dll")]

        public static extern bool SetLocalTime(ref SYSTEMTIME Time);

        [DllImport("Kernel32.dll")]

        public static extern void GetLocalTime(ref SYSTEMTIME Time);

    }

    public class SystemHelper

    {

        public static void SetLocalMachineTime(DateTime dt)

        {

            //转换System.DateTime到SYSTEMTIME

            SYSTEMTIME st = new SYSTEMTIME();

            st.FromDateTime(dt);

            //调用Win32 API设置系统时间

            Win32API.SetLocalTime(ref st);

        }

    }