Convert IPV6 to nibble format for PTR records

Question

I need to convert the ipv6 address to its nibble format for use when creating ptr entries dynamically. Here is the information I received from Wikipedia:

IPv6 Reverse Resolution

Reverse DNS lookup for IPv6 addresses use the special ip6.arpa domain. An IPv6 address is displayed as a name in this domain as a sequence of pieces in reverse order, represented as hexadecimal digits as subdomains. For example, the domain name of the pointer corresponds to the IPv6 2001 address: db8 :: 567: 89ab ba9.8.7.6.5.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.8.bd0.1.0.0.2.ip6.arpa .

The only thing I could find regarding nibbles was in the pack function, http://www.php.net/pack . I could not find solutions with examples from the search problem.

Any help is greatly appreciated.

Answer 1

Given a suitable modern version of PHP (> = 5.1.0 or 5.3+ on Windows), use the inet_pton function to parse the IPv6 address into a 16-byte array, and then use the standard string operators to cancel it.

 $ip = '2001:db8::567:89ab'; $addr = inet_pton($ip); $unpack = unpack('H*hex', $addr); $hex = $unpack['hex']; $arpa = implode('.', array_reverse(str_split($hex))) . '.ip6.arpa'; 

Answer 2

You can use the ipv6calc string ipv6calc (UNIX / Linux) from here .

For instance:

 $ ./ipv6calc --out revnibbles.arpa 2001:db8::1 No input type specified, try autodetection...found type: ipv6addr 1.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.8.bd0.1.0.0.2.ip6.arpa. 

You can paste this script to eat your direct zone files and create PTRs .

Answer 3

And this is the opposite, based on the large Alnitak code, as a function:

 function ptr_to_ipv6($arpa) { $mainptr = substr($arpa, 0, strlen($arpa)-9); $pieces = array_reverse(explode(".",$mainptr)); $hex = implode("",$pieces); $ipbin = pack('H*', $hex); $ipv6addr = inet_ntop($ipbin); return $ipv6addr; } 

Answer 4

I'm doing it:

 function expand($ip){ $hex = unpack("H*hex", inet_pton($ip)); $ip = substr(preg_replace("/([A-f0-9]{4})/", "$1:", $hex['hex']), 0, -1); return $ip; } function ipv6_reverse_calc($address){ $rev = chop(chunk_split(strrev(str_replace(':', '', expand($address))), 1, '.'), '.'); return "$rev.ip6.arpa"; } 

Answer 5

Well, from this example you can see that the nibble format is the full ipv6 address (including 0'd fields), the reverse, then separated by characters and separated by periods. So personally, I would just use a string representation and manipulate it as needed.