Michael Stapelberg
and 1 contributors

NAME

all-knowing-dns - Tiny DNS server for IPv6 Reverse DNS

SYNOPSIS

    all-knowing-dns [--configfile <path>] [--querylog]

DESCRIPTION

AllKnowingDNS provides reverse DNS for IPv6 networks which use SLAAC (autoconf), e.g. for a /64 network.

The problem with IPv6 reverse DNS and traditional nameservers is that the nameserver requires you to provide a zone file. Assuming you want to provide RDNS for a /64 network, you have 2**64 = 18446744073709551616 different usable IP addresses (a little less if you are using SLAAC). Providing a zone file for that, even in a very terse notation, would consume a huge amount of disk space and could not possibly be held in the memory of the computers we have nowadays.

AllKnowingDNS instead generates PTR and AAAA records on the fly. You only configure which network you want to serve and what your entries should look like.

OPTIONS

--configfile=path

Use path instead of /etc/all-knowing-dns.conf as configuration file.

--querylog

Enable logging every query to stdout (for debugging).

CONFIGURATION FILE (/etc/all-knowing-dns.conf)

The configuration file is wonderfully simple:

    # Configuration file for AllKnowingDNS v1.7

    listen 79.140.39.197
    listen 2001:4d88:100e:1::3
    
    # RaumZeitLabor
    network 2001:4d88:100e:ccc0::/64
        resolves to ipv6-%DIGITS%.nutzer.raumzeitlabor.de
        with upstream 2001:4d88:100e:1::2
    
    # Chaostreff
    network 2001:4d88:100e:cd1::/64
        resolves to ipv6-%DIGITS%.treff.noname-ev.de

This example contains all configuration directives. Let's go over them one by one:

listen address

Listens on the given address (IPv4 and IPv6 is supported) on port 53.

network network

Specifies that queries for PTR records within the given network should be answered (any query for an unconfigured network will be answered with NXDOMAIN). You need to specify at least the resolves to directive afterwards.

resolves to address

Specifies the address to which PTR records should resolve. The address needs to contain %DIGITS% exactly once. When answering AAAA queries, %DIGITS% will be parsed and converted back to an IPv6 address.

Example:

    network 2001:4d88:100e:ccc0::/64
        resolves to ipv6-%DIGITS%.nutzer.raumzeitlabor.de

Example query:

    The PTR query 2001:4d88:100e:ccc0:216:eaff:fecb:826 will resolve to
    ipv6-0216eafffecb0826.nutzer.raumzeitlabor.de
with upstream address

Before answering a PTR query for this network, AllKnowingDNS will ask the DNS server at address first, appending .upstream to the query.

Example:

    network 2001:4d88:100e:ccc0::/64
        resolves to ipv6-%DIGITS%.nutzer.raumzeitlabor.de
        with upstream 2001:4d88:100e:1::2

Example query:

    The PTR query 2001:4d88:100e:ccc0:219:dbff:fe43:2ec5 will make
    AllKnowingDNS ask for
    5.c.e.2.3.4.e.f.f.f.b.d.9.1.2.0.0.c.c.c.e.0.0.1. \
    8.8.d.4.1.0.0.2.ip6.arpa.upstream. at 2001:4d88:100e:1::2
    and relay the answer, if any.

DELEGATING ZONES

This section shows you how to delegate a zone in BIND9 or any DNS server with a compatible zone file syntax. To use AllKnowingDNS, you need to delegate the appropriate .ip6.arpa zone for your network and one regular domain.

REVERSE DELEGATION (.ip6.arpa)

    $ORIGIN .
    $TTL 604800     ; 1 week
    e.0.0.1.8.8.d.4.1.0.0.2.ip6.arpa IN SOA infra.in.zekjur.net. \
                                          hostmaster.zekjur.net. (
                                    20         ; serial
                                    604800     ; refresh (1 week)
                                    86400      ; retry (1 day)
                                    2419200    ; expire (4 weeks)
                                    604800     ; minimum (1 week)
                                    )
                            NS      libri.sur5r.net.
                            NS      infra.in.zekjur.net.

    ; net for RaumZeitLabor
    0.c.c.c.e.0.0.1.8.8.d.4.1.0.0.2.ip6.arpa. IN  NS        ipv6-rdns.zekjur.net.

FORWARD DELEGATION (.nutzer.raumzeitlabor.de)

    $TTL    6h
    raumzeitlabor.de    IN  SOA ns1.jpru.de.    hostmaster.jpru.de. (
                            2012030701
                            3h
                            30m
                            7d
                            1d )
        IN  NS  ns1.jpru.de.
        IN  NS  ns2.jpru.de.
        IN  A   195.49.138.121
        IN  MX  10  rzl.uugrn.org.
        IN  MX  20  up.uugrn.org.
        IN  MX  50  mail.uugrn.org.
        IN  MX  100 rzl.uugrn.org.

    nutzer.raumzeitlabor.de. IN NS ipv6-rdns.zekjur.net.

VERSION

Version 1.7

AUTHOR

Michael Stapelberg, <michael at stapelberg.de>

LICENSE AND COPYRIGHT

Copyright 2012 Michael Stapelberg.

This program is free software; you can redistribute it and/or modify it under the terms of the BSD license.