# 網絡逆向分析實驗3

## 實驗簡介
> 嘗試採用libnet向外部網絡發出構造的測試數據包(低速率)發送速率模式可以採用泊松及On /Off模型

## 實驗環境
* VirtualBox： Ubuntu
* Windows
* WireShark
* Libnet
* GCC

## 實驗流程
> 本實驗是在Ubuntu和Windows兩個平台上實現的。

1. 在Ubuntu上安裝Libnet
> sudo apt-get install libnet-dev

2. 在Ubuntu使用編寫C語言編寫Libnet程序

#include <stdio.h>
#include <string.h>
#include <libnet.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <math.h>
#include <limits.h>

void Sleep(int t);
int Fac(int N);
void P(int X, libnet_t *);

int main() {
    //1.初始化内存
    libnet_t *lib_handle = libnet_init(LIBNET_LINK_ADV,"enp0s3",NULL);

    //获取键盘输入
    char data[128]="Hello! Libnet";
    // printf("请输入数据:\n");
    // fgets(data,sizeof(data),stdin);
    data[strlen(data)]=0;
    int data_len = strlen(data)+strlen(data)%2; //将长度变为偶数

    //2.构建数据包:从应用层--->链路层
    //构建UDP数据(传输层)
    libnet_ptag_t ptag_udp =libnet_build_udp(8000,9000,8+data_len,0,data,data_len,lib_handle,0);
    //构建IPv4数据(网络层)
    libnet_ptag_t ptag_ip = libnet_build_ipv4(20+8+data_len,0,0,0,128,17,0,inet_addr("192.168.56.102"),inet_addr("192.168.56.1"),NULL,0,lib_handle,0);
    //构建以太网数据包(链路层)
    unsigned char src_mac[6]={0x08, 0x00, 0x27, 0x5f, 0x56, 0x19}; //虚拟机mac
    unsigned char dst_mac[6]={0xd0, 0x57, 0x7b, 0x1c, 0x08, 0x81};//windows的mac
    libnet_ptag_t ptag_mac = libnet_build_ethernet(dst_mac,src_mac,0x0800,NULL,0,lib_handle,0);

    int times = 15;

    int delay = 10000000;

    for (int k = 0; k < times; k++) {
        //3.发送帧数据
        P(k, lib_handle);
        Sleep(delay);
    }
    
    //4.释放资源
    libnet_destroy(lib_handle);

    puts("Success!");

    return 0;
}

void Sleep(int t) {
    for (int i = 0; i < t; i++) {
        puts("Waiting!");
    }
}

int Fac(int N) {

    if (N == 1 || N == 0) return 1;

    int n = 1;

    for (int i = 2; i <= N; i++) {
        n *= i;
    }

    return n;
}

void P(int X, libnet_t * lib_handle) {
    float e = 2.718282;

    float p = pow(4, X) / Fac(X);

    p *= pow(e, -4);

    p *= 100000;

    printf("%f\n", p);

    for (int i = 1; i <= p; i++) {
        puts("Writting!");
        libnet_write(lib_handle);
    }
}

3. 編譯Libnet代碼


4. 利用WireShark抓Libnet發送的包，