25 lines
744 B
Python
25 lines
744 B
Python
#!/usr/bin/env python3
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# Nico Schottelius, 2020-01-07
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# Detect the DNS64 prefix
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# Based on https://tools.ietf.org/html/draft-ietf-behave-nat64-discovery-heuristic-05
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#
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# How it works:
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# - ipv4only.arpa only has A records.
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# - a DNS64 server will add AAAA records
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# - we take this response (if any) and derive the IPv6 prefix from it
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#
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import dns.resolver
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import ipaddress
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if __name__ == '__main__':
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dns64_prefix = None
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answers = dns.resolver.query('ipv4only.arpa', 'AAAA')
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for rdata in answers:
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address = str(rdata)
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network = ipaddress.IPv6Network("{}/96".format(address),
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strict=False)
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# print("{}: {}".format(rdata, network))
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print("{}".format(network))
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