organize nameservers by asn

.github/workflows/whoami.yml

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+name: Collect stats on DNS servers using whoami.akamai.net
+
+on:
+  push:
+    paths:
+      - 'nameservers.txt'
+  workflow_dispatch:
+
+jobs:
+  file-updated:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v3
+      - name: Set up Python
+        uses: actions/setup-python@v4
+        with:
+          python-version: "3.x"
+      - name: Install ASN database
+        run: |
+          pip install pyasn
+          python3 pyasn_util_download.py --latestv46
+          python3 pyasn_util_convert.py --single rib.*.bz2 asn.db
+      - name: Publish stats
+        run: |
+          python3 public_dns_servers/whoami.py | tee nameservers_by_asn.json
+      - name: git add nameservers_by_asn.json
+        uses: EndBug/add-and-commit@v9
+        with:
+          add: "nameservers_by_asn.json"
+          default_author: github_actions
+          message: "refresh nameservers_by_asn.json"

public_dns_servers/whoami.py

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+import sys
+import json
+import dns.resolver
+import pyasn
+import ipaddress
+
+def query_dns(nameserver, domain):
+    resolver = dns.resolver.Resolver(configure=False)
+    resolver.timeout = 1
+    resolver.lifetime = 1
+    resolver.nameservers = [nameserver]
+    try:
+        answers = resolver.resolve(domain, 'A')
+        return str(answers[0])
+    except Exception as e:
+        return f"Error querying {nameserver}: {str(e)}"
+
+def main():
+    # List of DNS nameservers to query
+    nameservers = open('nameservers.txt').read().splitlines()
+
+    # Domain to query
+    domain = 'whoami.akamai.net'
+
+    asndb = pyasn.pyasn('asn.db')
+
+    asns = {}
+
+    try:
+        for nameserver in nameservers:
+            ip = query_dns(nameserver, domain)
+            if not ip.startswith('Error'):
+                try:
+                    asn, subnet = asndb.lookup(ip)
+                except Exception as e:
+                    print(f"Error getting subnet for {ip}: {str(e)}")
+                    continue
+                print(f"Nameserver {nameserver} uses IP {ip} (subnet: {subnet}, ASN: {asn})")
+                try:
+                    asns[asn].add(nameserver)
+                except KeyError:
+                    asns[asn] = {nameserver}
+            else:
+                print(ip)
+            print(file=sys.stderr)
+    finally:
+        asns = {k:sorted(v) for k,v in asns.items()}
+        print(json.dumps(asns, sort_keys=True, indent=2))
+
+if __name__ == "__main__":
+    main()