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TUCoPS :: Unix :: General :: neped.c

neped.c - Network Promiscuous Ethernet Detector




/* -----------------------------------------

     Network Promiscuous Ethernet Detector.

      Linux 2.0.x / 2.1.x, libc5 & GlibC

   -----------------------------------------

         (c) 1998 savage@apostols.org

   -----------------------------------------

          Toxyn Technologies Inc.



   Scan your subnet, and detect promiscuous

   machinez. It really works, not a joke.

   ----------------------------------------- */



/*

 * $Id: neped.c,v 1.2 1998/06/04 17:58:17 savage Exp $

 */



#include <stdio.h>

#include <string.h>

#include <unistd.h>

#include <sys/socket.h>

#include <sys/time.h>

#include <malloc.h>

#include <ctype.h>

#include <netinet/in.h>

#include <arpa/inet.h>

#include <netinet/tcp.h>

#include <net/if.h>

#include <sys/ioctl.h>

#include <fcntl.h>

#include <time.h>

#define ETH_P_ARP       0x0806

#define MAX_PACK_LEN    2000

#define ETHER_HEADER_LEN 14

#define ARPREQUEST      1

#define ARPREPLY        2

#define perr(s) fprintf(stderr,s)



struct arp_struct

  {

    u_char  dst_mac[6];

    u_char  src_mac[6];

    u_short pkt_type;

    u_short hw_type;

    u_short pro_type;

    u_char  hw_len;

    u_char  pro_len;

    u_short arp_op;

    u_char  sender_eth[6];

    u_char  sender_ip[4];

    u_char  target_eth[6];

    u_char  target_ip[4];

  };



union

  {

    u_char full_packet[MAX_PACK_LEN];

    struct arp_struct arp_pkt;

  }

a;



#define full_packet a.full_packet

#define arp_pkt a.arp_pkt



char *

inetaddr ( u_int32_t ip )

{

  struct in_addr in;

  in.s_addr = ip;

  return inet_ntoa(in);

}



char *

hwaddr (u_char * s)

{

  static char buf[30];

  sprintf (buf, "%02X:%02X:%02X:%02X:%02X:%02X", s[0], s[1], s[2], s[3],

s[4], s[5]);

  return buf;

}



void

main (int argc, char **argv)

{

  int rec;

  int len, from_len, rsflags;

  struct ifreq if_data;

  struct sockaddr from;

  u_int8_t myMAC[6];

  u_int32_t myIP, myNETMASK, myBROADCAST, ip, dip;



  if (getuid () != 0)

    {

      perr ("You must be root to run this program!\n");

      exit (0);

    }

  if (argc != 2)

    {

      fprintf(stderr,"Usage: %s eth0\n", argv[0]);

      exit (0);

    }



  if ((rec = socket (AF_INET, SOCK_PACKET, htons (ETH_P_ARP))) < 0)

    {

      perror("socket");

      exit (0);

    }



  printf ("----------------------------------------------------------\n");

  strcpy (if_data.ifr_name, argv[1]);

  if (ioctl (rec, SIOCGIFHWADDR, &if_data) < 0) {

    perr ("can't get HW addres of my interface!\n");

    exit(1);

  }

  memcpy (myMAC, if_data.ifr_hwaddr.sa_data, 6);

  printf ("> My HW Addr: %s\n", hwaddr (myMAC));



  if (ioctl (rec, SIOCGIFADDR, &if_data) < 0) {

    perr ("can't get IP addres of my interface!\n");

    exit(1);

  }

  memcpy ((void *) &ip, (void *) &if_data.ifr_addr.sa_data + 2, 4);

  myIP = ntohl (ip);

  printf ("> My IP Addr: %s\n", inetaddr(ip));



  if (ioctl (rec, SIOCGIFNETMASK, &if_data) < 0)

    perr ("can't get NETMASK addres of my interface!\n");

  memcpy ((void *) &ip, (void *) &if_data.ifr_netmask.sa_data + 2, 4);

  myNETMASK = ntohl (ip);

  printf ("> My NETMASK: %s\n", inetaddr(ip));



  if (ioctl (rec, SIOCGIFBRDADDR, &if_data) < 0)

    perr ("can't get BROADCAST addres of my interface!\n");

  memcpy ((void *) &ip, (void *) &if_data.ifr_broadaddr.sa_data + 2, 4);

  myBROADCAST = ntohl (ip);

  printf ("> My BROADCAST: %s\n", inetaddr(ip));



  if ((rsflags = fcntl (rec, F_GETFL)) == -1)

    {

      perror ("fcntl F_GETFL");

      exit (1);

    }



  if (fcntl (rec, F_SETFL, rsflags | O_NONBLOCK) == -1)

    {

      perror ("fcntl F_SETFL");

      exit (1);

    }





  printf ("----------------------------------------------------------\n");

  printf ("> Scanning ....\n");

  for (dip = (myIP & myNETMASK) + 1; dip < myBROADCAST; dip++)

    {

      bzero(full_packet, MAX_PACK_LEN);



      memcpy (arp_pkt.dst_mac, "\0\6\146\3\23\67", 6); /*

00:06:66:03:13:37 :) */

      memcpy (arp_pkt.src_mac, myMAC, 6);

      arp_pkt.pkt_type = htons( ETH_P_ARP );

      arp_pkt.hw_type = htons( 0x0001 );

      arp_pkt.hw_len = 6;

      arp_pkt.pro_type = htons( 0x0800 );

      arp_pkt.pro_len = 4;

      arp_pkt.arp_op = htons (ARPREQUEST);

      memcpy (arp_pkt.sender_eth, myMAC, 6);

      ip = htonl (myIP);

      memcpy (arp_pkt.sender_ip, &ip, 4);

      memcpy (arp_pkt.target_eth, "\0\0\0\0\0\0", 6);

      ip = htonl (dip);

      memcpy (arp_pkt.target_ip, &ip, 4);



      strcpy(from.sa_data, argv[1]);

      from.sa_family = 1;



      if( sendto (rec, full_packet, sizeof (struct arp_struct), 0, &from,

sizeof(from)) < 0)

          perror ("sendto");



      usleep (333);



      len = recvfrom (rec, full_packet, MAX_PACK_LEN, 0, &from,

&from_len);

      if (len <= ETHER_HEADER_LEN)

        continue;



      memcpy (&ip, arp_pkt.target_ip, 4);



      if (ntohs (arp_pkt.arp_op) == ARPREPLY

          && ntohl (ip) == myIP)

        {

          memcpy (&ip, arp_pkt.sender_ip, 4);

          printf ("*> Host %s, %s **** Promiscuous mode detected !!!\n",

                  inetaddr (ip),

                  hwaddr (arp_pkt.sender_eth));

        }



    }



  printf ("> End.\n");



  exit (0);

}









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