Updated IP, PDU and PacketSender so as to send forged ip packets successfully

include/utils.h

@@ -10,6 +10,14 @@ namespace Tins {
     namespace Utils {
         uint32_t ip_to_int(const std::string &ip);
         std::string ip_to_string(uint32_t ip);
+
+        inline uint32_t ntohl(uint32_t address) {
+            return (((address & 0xff000000) >> 24) |
+                    ((address & 0x00ff0000) >> 8)  |
+                    ((address & 0x0000ff00) << 8)  |
+                    ((address & 0x000000ff) << 24));
+        }
+
     };
 };