发送arp请求报文

 (1)报文格式

(2)代码如下:

#include <stdio.h>
#include <stdlib.h>
#include <sys/socket.h>
#include <sys/types.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <net/ethernet.h>
#include <netpacket/packet.h>
#include <string.h>
#include <net/if.h>

#define SRC_MAC  { 0x00,0x0C,0x29,0x6F,0x57,0xE7 }//源MAC地址
#define DEST_MAC { 0x00,0x0C,0x29,0xD3,0xD6,0xF7 }//目的MAC地址

struct arppacket
{
        unsigned char dest_mac[ETH_ALEN];//接收方MAC
        unsigned char src_mac[ETH_ALEN];//发送方MAC
        unsigned short type;         //0x0806是ARP帧的类型值
        unsigned short ar_hrd;//硬件类型 - 以太网类型值0x1
        unsigned short ar_pro;//上层协议类型 - IP协议(0x0800)
        unsigned char  ar_hln;//MAC地址长度
        unsigned char  ar_pln;//IP地址长度
        unsigned short ar_op;//操作码 - 0x1表示ARP请求包,0x2表示应答包
        unsigned char  ar_sha[ETH_ALEN];//发送方mac
        unsigned char ar_sip[4];//发送方ip
        unsigned char ar_tha[ETH_ALEN];//接收方mac
        unsigned char ar_tip[4];//接收方ip
} __attribute__ ((__packed__));
int main(int argc,char *argv[])
{
    int fd = 0;
    struct in_addr s,r;
    struct sockaddr_ll sl;

    struct arppacket arp={
                DEST_MAC,
                SRC_MAC,
                htons(0x0806),
                htons(0x01),
                htons(0x0800),
                ETH_ALEN,
                4,
                htons(0x01),
                SRC_MAC,
                {0},
                DEST_MAC,
                {0}
    };

    fd = socket(AF_PACKET,SOCK_RAW,htons(ETH_P_ALL));
    if(fd < 0)
    {
        printf("socket error\n");
        return -1;
    }
    memset(&sl, 0, sizeof(sl));

    inet_aton("192.168.11.220", &s);
    memcpy(&arp.ar_sip, &s, sizeof(s));

    inet_aton("192.168.11.192", &r);
    memcpy(&arp.ar_tip, &r, sizeof(r));


    sl.sll_family = AF_PACKET;
    sl.sll_ifindex = IFF_BROADCAST;
	
	while(1)
    {
        if(sendto(fd,&arp, sizeof(arp), 0, (struct sockaddr*)&sl, sizeof(sl)) <= 0)
        {
            printf("send error\n");
        }
        else
           printf("send success\n");

        sleep(1);
    }

    close(fd);

    return 0;
}