Add script to detect DNS64 prefix

detect-dns64-prefix.py

@@ -0,0 +1,19 @@
+#!/usr/bin/env python3
+# Nico Schottelius, 2020-01-07
+# Detect the DNS64 prefix
+# Based on https://tools.ietf.org/html/draft-ietf-behave-nat64-discovery-heuristic-05
+
+import dns.resolver
+import ipaddress
+
+
+if __name__ == '__main__':
+    dns64_prefix = None
+    answers = dns.resolver.query('ipv4only.arpa', 'AAAA')
+
+    for rdata in answers:
+        address = str(rdata)
+        network = ipaddress.IPv6Network("{}/96".format(address),
+                                        strict=False)
+        # print("{}: {}".format(rdata, network))
+        print("{}".format(network))