OpenNetAdmin

In order to support the classless IN-ADDR.ARPA delegation, it's required to (1) generate a bind config with domain name like '192/26.2.0.192.in-addr.arpa.' -- for 192.0.2.192/26 being delegated to ONA's DNS server.
Another change (2) is to provide ip numbers in PTR records relative to $ORIGIN, instead of giving FQDN to the left from 'PTR'.

So, ideally we need something like this for the network 192.123.161.0/25
==========
$ORIGIN 0/25.161.123.192.in-addr.arpa.
$TTL 86400
;Serial number is current unix timestamp (seconds since UTC)

@ IN SOA server.example.com. hostmaster.example.com. (1259378388 86400 3600 3600 3600)

0/25.161.123.192.in-addr.arpa. IN NS server.example.com.
1 IN PTR gw.example.com.
2 IN PTR host1.example.com.
==========

Having that, we can add to header's named.conf:
zone "0/25.161.123.192.in-addr.arpa" in {
type master;
file "/etc/bind/zone_data/named-161.123.192.in-addr.arpa";
// allow-transfer { slave_dns; }; // to support slave dns
};


========== solution ==========
The (1) change should be made in www/include/functions_general.inc.php to allow '/' symbol in a host name:

diff /tmp/original/ona/www/include/functions_general.inc.php functions_general.inc.php
887c887
< if (preg_match('/^([a-z0-9_\*]([a-z0-9_\.\-]*))?[a-z0-9]$/', $string)) {
---
> if (preg_match('/^([a-z0-9_\*]([a-z0-9_\.\-\/]*))?[a-z0-9]$/', $string)) {

==
The (2) change is made in build_bind.inc.php.diff
$ cat build_bind.inc.php.diff
415c415,418
< $text .= sprintf("%-50s %-8s IN %-8s %s.%-30s %s\n" ,ip_mangle($interface['ip_addr'],'flip').'.in-addr.arpa.',$dnsrecord['ttl'],$dnsrecord['type'],$ptr['name'],$ptr['domain_fqdn'].'.',$dnsrecord['notes']);
---
> # $text .= sprintf("%-50s %-8s IN %-8s %s.%-30s %s\n" ,ip_mangle($interface['ip_addr'],'flip').'.in-addr.arpa.',$dnsrecord['ttl'],$dnsrecord['type'],$ptr['name'],$ptr['domain_fqdn'].'.',$dnsrecord['notes']);
> $ip_last_digit = ip_mangle($interface['ip_addr'],'flip');
> $ip_last_digit = substr($ip_last_digit, 0, strpos($ip_last_digit,'.'));
> $text .= sprintf("%-50s %-8s IN %-8s %s.%-30s %s\n" ,$ip_last_digit,$dnsrecord['ttl'],$dnsrecord['type'],$ptr['name'],$ptr['domain_fqdn'].'.',$dnsrecord['notes']);

===

It works for me, so it might be that i forgot to mention something else. If it does not work for you, then please look through my full diff at http://netserver.chtd.tpu.ru/ona_diff/ona.diff It gives support for both UTF-8 symbols and classless delegation.