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i'll try to explain my problem with examples: when i'm using ipv6calc to build a reverse domain this is what i want to get:

$ ipv6calc --out revnibbles.arpa 2001:0db8:85a3::/48 No input type specified, try autodetection...found type: ipv6addr 3.a.5.8.8.b.d.0.1.0.0.2.ip6.arpa. .

heres an example w/o given prefix (128 default) to see the difference

$ ipv6calc --out revnibbles.arpa 2001:0db8:85a3:: No input type specified, try autodetection...found type: ipv6addr 0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.3.a.5.8.8.b.d.0.1.0.0.2.ip6.arpa.

now im trying to build the reverse domain in python with the ipaddress module and with a given prefix like above (important)

import ipaddress print(ipaddress.IPv6Network(u"2001:0db8:85a3::/48").reverse_pointer)

output is

8.4./.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.3.a.5.8.8.b.d.0.1.0.0.2.ip6.arpa

Seems like the module did not consider that. I have also tried the module IPy, but its buggy as hell and not usable in my opinion. Does anyone have an idea how to solve that? i would prefer one without the usage of shell commands (ipv6calc).

Thank you in advance

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    I disagree with the close vote. This question already contains a MCVE which clearly demonstrates the problem, and how it differs from the desired result. My Python is not quite strong enough to solve it though. Commented Jun 3, 2019 at 15:28

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The reverse_pointer is implemented that way:

 def _reverse_pointer(self): """Return the reverse DNS pointer name for the IPv6 address. This implements the method described in RFC3596 2.5. """ reverse_chars = self.exploded[::-1].replace(':', '') return '.'.join(reverse_chars) + '.ip6.arpa'

So it clearly will not take into account the prefix. Note that it specifically speaks about IPv6 address, not network/prefix.

First you will have a better answer by doing:

print(ipaddress.IPv6Network(u"2001:0db8:85a3::/48").network_address.reverse_pointer)

which gives: 0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.3.a.5.8.8.b.d.0.1.0.0.2.ip6.arpa which is proper version, even if not what you want.

You either need to subclass IPv6Network and rewrite _reverse_pointer to your liking or muck directly with its current result as the following, that could work but has edge cases:

print(ipaddress.IPv6Network(u"2001:0db8:85a3::/48").network_address.reverse_pointer[(2*(128-48)/4):]) 3.a.5.8.8.b.d.0.1.0.0.2.ip6.arpa

because the full result is 32 nibbles (hexadecimal digit) separated by a dot (besides the final .ip6.arpa), and 128-48 is the number of bits for the non prefix part, and since the previous is in bits, you need to count bytes in hexadecimal so /4 but *2 because each nibble is present with a following dot.

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i had a simlar solution network = ipaddress.IPv6Network('2001:db8:85a3::/48', False); '.'.join(network.network_address.reverse_pointer.split('.')[32-(network.prefixlen//4):]) which is still not satisfying. if you compare the output with ipv6calc and some special prefixes (49 for example) neither yours nor mine works right

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