在c#用raw socket进行sniff嗅探（一）

raw socket 三部曲：

socket = new Socket(AddressFamily.InterNetwork, SocketType.Raw, ProtocolType.IP);

socket.Bind(new IPEndPoint(IPAddress.Parse(IP), 0));

同步下：rcv_size = socket.Receive(buffer);

异步下：socket.Begin***

实现过程不难，难点是捕获后对数据报的分析，过滤的工作。

ps：网络层ip数据报格式如下：ip header＋××header(如TCP header) + Data

今天存在问题如下：嗅觉不灵敏，不知道是设置不对还是raw socket效果本身就是这样，等待考究……

今天研究到此结束，待续……

附代码：

RawSocket.cs

using System;
using System.Collections.Generic;
using System.Text;
using System.Net;
using System.Net.Sockets;
using System.Runtime.InteropServices;

namespace RawSocket
...{

        /// <summary>
        /// @author segment

        /// </summary>
    [StructLayout(LayoutKind.Explicit)]
    public struct IpHeader
    ...{
        [FieldOffset(0)]
        public byte ip_verlen; // IP version and IP Header length
        [FieldOffset(1)]
        public byte ip_tos; // Type of service
        [FieldOffset(2)]
        public ushort ip_totallength; // total length of the packet
        [FieldOffset(4)]
        public ushort ip_id; // unique identifier
        [FieldOffset(6)]
        public ushort ip_offset; // flags and offset
        [FieldOffset(8)]
        public byte ip_ttl; // Time To Live
        [FieldOffset(9)]
        public byte ip_protocol; // protocol (TCP, UDP etc)
        [FieldOffset(10)]
        public ushort ip_checksum; //IP Header checksum
        [FieldOffset(12)]
        public uint ip_srcaddr; //Source address
        [FieldOffset(16)]
        public uint ip_destaddr;//Destination Address
    }

    class RawSocket
    ...{
        Socket socket;
        String IP = "218.20.242.189";
        private String StandardIP(uint ip)
        ...{
            byte[] b_ip = new byte[4];
            b_ip[0] = (byte)(ip & 0x000000ff);
            b_ip[1] = (byte)((ip & 0x0000ff00) >> 8);
            b_ip[2] = (byte)((ip & 0x00ff0000)>>16);
            b_ip[3] = (byte)((ip & 0xff000000)>>24);
            return b_ip[0].ToString() + "." + b_ip[1].ToString() + "." + b_ip[2].ToString() + "." + b_ip[3].ToString();
        }
        unsafe private void ParseReceive(byte[]buffer,int size)
        ...{
            if (buffer == null) return;
            fixed (byte*pbuffer = buffer)
            ...{
                IpHeader* ip_header = (IpHeader*)pbuffer;
                int protocol = ip_header->ip_protocol;
                uint ip_srcaddr = ip_header->ip_srcaddr, ip_destaddr = ip_header->ip_destaddr, header_len = 0;
                string out_string = "";
                short src_port = 0, dst_port = 0;
                IPAddress tmp_ip;
                string from_ip="", to_ip="";
                from_ip = ip_header->ip_srcaddr.ToString();
                switch (protocol)
                ...{
                    case 1: out_string = "ICMP:"; break;
                    case 2: out_string = "IGMP:"; break;
                    case 6:
                        out_string = "TCP:";
                        break;
                    case 17: out_string = "UDP:";
                        break;
                    default: out_string = "UNKNOWN"; break;
                }
//                System.Console.WriteLine(out_string + "from ip:" + IPAddress.Parse(from_ip).ToString() + " to ip:" + IPAddress.Parse(to_ip).ToString());
                System.Console.WriteLine(out_string + "src:" + StandardIP(ip_srcaddr) + "dest:" + StandardIP(ip_destaddr));
            }
            
        }
        public void ShutDown()
        ...{
            if(socket != null)
            ...{
                try
                ...{
                    socket.Shutdown(SocketShutdown.Both);
                    socket.Close();
                }
                catch(Exception)
                ...{
                    System.Console.WriteLine("关闭socket错误!");
                }

            }
        }
        public void Run()
        ...{
            System.Console.WriteLine("Raw Socket running...");
            socket = new Socket(AddressFamily.InterNetwork, SocketType.Raw, ProtocolType.IP);
            byte[] buffer = new byte[4096];
            int rcv_size = 0;
            // socket.Blocking = false;
            socket.Bind(new IPEndPoint(IPAddress.Parse(IP), 0));
            while (true)
            ...{
                System.Console.WriteLine("开始新一次循环");
                try
                ...{
                    //socket.BeginReceive(buffer, 0, 10, SocketFlags.None, Callback, null);
                    rcv_size = socket.Receive(buffer);
                    ParseReceive(buffer, rcv_size);
                }
                catch (Exception e)
                ...{
                    System.Console.WriteLine("异常：" + e.Message);
                    return;
                }
                //System.Threading.Thread.Sleep(500);
                //System.Console.WriteLine("接收到:" + rcv_size.ToString());
            }
        }
        ~RawSocket()
        ...{
            ShutDown();
        }
    }
}

 

使用方法：

 

public static void Main(String[] args)
        ...{
            RawSocket socket = new RawSocket();
            socket.Run();

        }