利用Raw Socket 抓包

#include <sys/socket.h>
#include <sys/ioctl.h>
#include <fcntl.h>
#include <unistd.h>
#include <netinet/if_ether.h>
#include <netinet/ip.h>
#include <netinet/udp.h>
#include <netinet/tcp.h>
#include <net/if.h>
#include <netdb.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <linux/if_packet.h>
#include <linux/errno.h>

int socket_init(void);
int showpacket(unsigned char* buffer);
int sendfd,sock;
struct sockaddr_ll in_addr;
struct sockaddr_ll dest;
struct ifreq ifr;


int main(argc,argv)
   int argc;
   char *argv[];
{
   socklen_t destlen;
   struct ethhdr *eth_hdr;
   int recv_len, socklen,flag = 0,on=1,n=0;
   unsigned char buffer[65536];
   int myflag=0;
   struct packet_mreq mr;
   int state=0;
   int recv_buf_len,buflen;
   int i=0;
   
   memset(&mr,0,sizeof(mr));
    socklen=sizeof(struct sockaddr_ll);
   
   if(argc < 2)
   {
       printf("\n invalid argument!! \n");
       exit(0);
   }

   sock = socket_init();
   sendfd=socket(PF_PACKET,SOCK_RAW,htons(ETH_P_ALL));
  
  strcpy(ifr.ifr_name,"eth0");
   ioctl(sendfd,SIOCGIFINDEX,&ifr);
   mr.mr_ifindex=ifr.ifr_ifindex;
   mr.mr_type=PACKET_MR_PROMISC;
  if(setsockopt(sendfd,SOL_PACKET,PACKET_ADD_MEMBERSHIP,&mr,sizeof(mr))==-1)
     {
       perror(" can not set to promisc");
       exit(0);
     }
    if(strcmp(argv[1], "all") == 0)
        flag = 0;
   else if(strcmp(argv[1], "debug") == 0)
        flag = 1;
   else {
       printf("\n wrong argument!!\n");
       exit(0);
   }
   while(1)
   {
       memset(&dest, 0x0, socklen);
       memset(&in_addr, 0x0, socklen);
        recv_len = recvfrom(sock, buffer, sizeof(buffer), 0,
           (struct sockaddr *)&in_addr, &socklen);
        showpacket(buffer);
       if(in_addr.sll_pkttype==PACKET_OUTGOING){printf("won't send me again;\n");continue;}
        dest.sll_family=AF_PACKET;
        dest.sll_ifindex =ifr.ifr_ifindex;
        dest.sll_halen=htons(ETH_HLEN);
       memmove(&dest.sll_addr,buffer,sizeof(buffer[0])*8);
        n=sendto(sendfd,buffer,recv_len,0,(struct sockaddr*)&dest,sizeof(dest));
      printf(" send n=%d\n",n);

   }
   return 0;
}

int socket_init()
{
   struct ifreq ifr;
   int sock;
   memset(&ifr, 0x0, sizeof(struct ifreq));

   if((sock = socket(PF_PACKET, SOCK_RAW, htons(0x0003))) < 0)
   {
       perror(" socket ");
       exit(0);
   }

   strcpy(ifr.ifr_name, "eth0");
   if(ioctl(sock, SIOCGIFFLAGS, &ifr) == -1)
   {
       perror("siocgifflags");
       exit(0);
   }

   
    ifr.ifr_flags |= IFF_PROMISC;
   if(ioctl(sock, SIOCSIFFLAGS, &ifr) == -1)
   {
       perror("fejwaio?");
       exit(0);
   }
   return sock;
}

int showpacket(unsigned char* buffer)
{
   int i=0;
   unsigned char buff[50];
   memmove(buff,buffer,50);
   for(i=0;i<50;i++)
   {
   if(i==25)printf("\n");
       printf("%2x ",buff[i]);
   }
   printf("\n");
}