[Pdns-users] Reverse Record Generator

Stefan Schmidt zaphodb at zaphods.net
Wed Jan 12 15:10:50 UTC 2011

On Tue, Jan 11, 2011 at 04:12:13PM -0500, Josh Barron wrote:
> The issue at hand is, with my initial deployment, we converted from BIND
> to PowerDNS.  The BIND setup used GENERATE statements, and it was easy
> to utilize the zone2sql scripts in order to parse the statements and
> generate the necessary records.  That is not the case with the other
> servers, in fact some of our subnets do not have any PTR records at
> all!!  We are talking on the order of several dozen class B's.
> Is there a tool that you can recommend where I can quickly resolve this,
> or should I just write some zone files for the records, and have the
> zone2sql script parse and import them into the master PDNS table.

For simple generation of records you could use zone transfers via AXFR from
BIND to PowerDNS initially by adding the domain as type slave to the domains
table and set it to NATIVE or MASTER afterwards.

What i did is a PowerDNS pipe backend that basically generates djb
walldns-style [1] forward and reverse records for a given CIDR network
dynamically i.e. at query time.
I initially published it in this [2] reply to a post on the NANOG mailing
list and lately revamped it and added IPv4 support to this version [3] created
for the 27C3, i just put on google code.
Over a generated zone this has the advantage that you do not need the
potentially petabytes of storage for say the full dns records of a /32 IPv6
Also due to the nature of PowerDNS you can put this pipe backend last in line
of backends on the launch= configuration line [4] and every backend specified
before it will get asked the question first and if for example your gmysql
backend is able to answer the query this response will get chosen of the one
from the pipe backend.
You can therefore "overload" the walldns style forward and reverse records
with more specific data just for some hosts.

[1] http://cr.yp.to/djbdns/walldns.html
[2] http://seclists.org/nanog/2010/Sep/335
[3] http://code.google.com/p/pdns-dynamic-reverse-backend/source/browse/pdns-dynamic-reverse-backend.py
[4] http://mailman.powerdns.com/pipermail/pdns-users/2010-December/007280.html

best regards,
If vegetarians eat vegetables, what do humanitarians eat?
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