From fe27d294b1ca5884586a8713c169780030d3b7bc Mon Sep 17 00:00:00 2001
From: Nico Schottelius <nico@nico-notebook.schottelius.org>
Date: Tue, 7 Jan 2020 18:07:34 +0100
Subject: [PATCH] Add script to detect DNS64 prefix

---
 detect-dns64-prefix.py | 19 +++++++++++++++++++
 1 file changed, 19 insertions(+)
 create mode 100644 detect-dns64-prefix.py

diff --git a/detect-dns64-prefix.py b/detect-dns64-prefix.py
new file mode 100644
index 0000000..e5bd179
--- /dev/null
+++ b/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))