const int SOCKET_ERROR = -1;        const int ICMP_ECHO = 8;        public string PingHost(string host)        {            IPHostEntry serverHE, fromHE;            Socket socket = new Socket(AddressFamily.InterNetwork, SocketType.Raw, ProtocolType.Icmp);            socket.SetSocketOption(SocketOptionLevel.Socket, SocketOptionName.SendTimeout, 3000);            socket.SetSocketOption(SocketOptionLevel.Socket, SocketOptionName.ReceiveTimeout, 3000);            try            {                serverHE = Dns.GetHostEntry(host);             }            catch (Exception)            {                return "Host not found";            }            //用IP地址和端口号构造IPEndPoint对象            EndPoint epServer = new IPEndPoint(serverHE.AddressList[0], 1555);            fromHE = Dns.GetHostEntry(Dns.GetHostName());              //Dns.GetHostName()获取本地计算机的主机名            //提供的 AddressFamily InterNetworkV6 的终结点对于此套接字无效，请改用 InterNetwork。            ///改为 IPV4            EndPoint EndPointFrom = new IPEndPoint(fromHE.AddressList[1], 80);            int PacketSize = 0;            IcmpPacket packet = new IcmpPacket();            packet.Type = ICMP_ECHO; //8            packet.SubCode = 0;            packet.CheckSum = UInt16.Parse("0");            packet.Identifier = UInt16.Parse("45");            packet.SequenceNumber = UInt16.Parse("0");            int PingData = http://www.mamicode.com/32;            packet.Data = new Byte[PingData];            //初始化数据包            for (int i = 0; i < PingData; i++)            {                packet.Data[i] = (byte)‘#‘;            }            PacketSize = PingData + 8;            Byte[] icmp_pkt_buffer = new Byte[PacketSize];            Int32 Index = 0;            Index = Serialize(packet, icmp_pkt_buffer, PacketSize, PingData);            if (Index == -1)            {                return "Error Creating Packet";            }            Double double_length = Convert.ToDouble(Index);            Double dtemp = Math.Ceiling(double_length / 2);            int cksum_buffer_length = Convert.ToInt32(dtemp);            //创建一个字节数组            UInt16[] cksum_buffer = new UInt16[cksum_buffer_length];            int icmp_header_buffer_index = 0;            for (int i = 0; i < cksum_buffer_length; i++)            {                cksum_buffer[i] = BitConverter.ToUInt16(icmp_pkt_buffer, icmp_header_buffer_index);                icmp_header_buffer_index += 2;            }            UInt16 u_cksum = CheckSum(cksum_buffer, cksum_buffer_length);            packet.CheckSum = u_cksum;            Byte[] sendbuf = new Byte[PacketSize];            //再次校验包的尺寸            Index = Serialize(packet, sendbuf, PacketSize, PingData);            if (Index == -1)            {                return "Error Creating Packet";            }            int dwStart = 0, dwStop = 0;            dwStart = System.Environment.TickCount; // Start timing            int nBytes = 0;            if ((nBytes = socket.SendTo(sendbuf, PacketSize, 0, epServer)) == SOCKET_ERROR)            {                return "Socket Error: cannot send Packet";            }            Byte[] ReceiveBuffer = new Byte[256];            nBytes = 0;            bool recd = false;            int timeout = 0;            while (!recd)            {                try                {                    //接收数据                    nBytes = socket.ReceiveFrom(ReceiveBuffer, 256, SocketFlags.None, ref EndPointFrom);                    if (nBytes == SOCKET_ERROR)                    {                        return "Host not Responding";                    }                    else if (nBytes > 0)                    {                        dwStop = System.Environment.TickCount - dwStart; // stop timing                        return "Reply from " + epServer.ToString() + " in "                         + dwStop + "ms.  Received: " + nBytes + " Bytes.";                    }                    timeout = System.Environment.TickCount - dwStart;                    if (timeout > 3000)                    {                        return "Time Out";                    }                }                catch (SocketException e)                {                    return "Time Out";                }            }            //关闭连接            socket.Close();            return "";        }        public static Int32 Serialize(IcmpPacket packet, Byte[] Buffer, Int32 PacketSize, Int32 PingData)        {            Int32 cbReturn = 0;            int Index = 0;            Byte[] b_type = new Byte[1];            b_type[0] = packet.Type;            Byte[] b_code = new Byte[1];            b_code[0] = packet.SubCode;            Byte[] b_cksum = BitConverter.GetBytes(packet.CheckSum);            Byte[] b_id = BitConverter.GetBytes(packet.Identifier);            Byte[] b_seq = BitConverter.GetBytes(packet.SequenceNumber);            Array.Copy(b_type, 0, Buffer, Index, b_type.Length);            Index += b_type.Length;            Array.Copy(b_code, 0, Buffer, Index, b_code.Length);            Index += b_code.Length;            Array.Copy(b_cksum, 0, Buffer, Index, b_cksum.Length);            Index += b_cksum.Length;            Array.Copy(b_id, 0, Buffer, Index, b_id.Length);            Index += b_id.Length;            Array.Copy(b_seq, 0, Buffer, Index, b_seq.Length);            Index += b_seq.Length;            //复制数据                     Array.Copy(packet.Data, 0, Buffer, Index, PingData);            Index += PingData;            if (Index != PacketSize)            {                cbReturn = -1;                return cbReturn;            }            cbReturn = Index;            return cbReturn;        }        /// <summary>        ///  校验方法         /// </summary>        public static UInt16 CheckSum(UInt16[] buffer, int size)        {            Int32 cksum = 0;            int counter;            counter = 0;            while (size > 0)            {                UInt16 val = buffer[counter];                cksum += Convert.ToInt32(buffer[counter]);                counter += 1;                size -= 1;            }            //右移16位            cksum = (cksum >> 16) + (cksum & 0xffff);            cksum += (cksum >> 16);            return (UInt16)(~cksum);//二进制取反：按位求补        }    public class IcmpPacket    {        public Byte Type;        public Byte SubCode;        public UInt16 CheckSum;        public UInt16 Identifier;        public UInt16 SequenceNumber;        public Byte[] Data;    }