coredns-auto-aaaa-and-ptr

coredns-auto-aaaa-and-ptr

This is a fork of https://github.com/vlcty/coredns-auto-ipv6-ptr. Added support for AAAA records for the dynamic PTR hostnames.

coredns-auto-ipv6-ptr

Some services require that a RDNS request resolves to a PTR record. With this CoreDNS plugin, you can generate these PTR records on the fly based on the requested IPv6 address. The plugin translates the requested address and appends a suffix. Additionally, you can create a so-called presets file to answer with a "real" record if a specific request is received.

Examples:

1. 2001:db8:300:b002:5054:ff:fe4b:db44 could be translated to 2001-0db8-0300-b002-5054-00ff-fe4b-db44.mydomain.tld
2. 2001:db8:300:b002:5054:ff:fe4b:db45 could be translated to myhost.mydomain.tld via the presets file

Presets

Each line in a presets file contains a manual override seperated by a comma. The first part contains the request and the second part contains the value which should be returned. For example:

5.4.b.d.b.4.e.f.f.f.0.0.4.5.0.5.2.0.0.b.0.0.3.0.8.b.d.0.1.0.0.2.ip6.arpa.;myhost.mydomain.tld
6.4.b.d.b.4.e.f.f.f.0.0.4.5.0.5.2.0.0.b.0.0.3.0.8.b.d.0.1.0.0.2.ip6.arpa.;firewall.mydomain.tld

Translation process

Let's say the plugin receives a PTR request for 4.4.b.d.b.4.e.f.f.f.0.0.4.5.0.5.2.0.0.b.0.0.3.0.8.b.d.0.1.0.0.2.ip6.arpa.. If there is a preset found the preset value will be used in the anwer. If there is none the regular translation process starts:

1. Strip .ip6.arpa.: 4.4.b.d.b.4.e.f.f.f.0.0.4.5.0.5.2.0.0.b.0.0.3.0.8.b.d.0.1.0.0.2
2. Remove all dots: 44bdb4efff004505200b00308bd01002
3. Reverse the string: 20010db80300b002505400fffe4bdb44
4. Add hyphens: 2001-0db8-0300-b002-5054-00ff-fe4b-db44
5. Append the suffix and return the result: 20010db80300b002505400fffe4bdb44.mydomain.tld

Corefile example

Possible plugin arguments:

Let's say your provider allocated 2001:db8:300:b000::/56 to you. You sliced two subnets out of it:

1. 2001:db8:300:b000::/64 => lan.myhost.tld
2. 2001:db8:300:b001::/64 => servers.myhost.tld

You Corefile would look something like this:

0.0.0.b.0.0.3.0.8.b.d.0.1.0.0.2.ip6.arpa {
    log
    autoipv6ptr {
        suffix lan.mydomain.tld
    }
}

1.0.0.b.0.0.3.0.8.b.d.0.1.0.0.2.ip6.arpa {
    log
    autoipv6ptr {
        suffix servers.mydomain.tld
        presetsfile /var/lib/coredns/presets.servers.mydomain.tld
        ttl 60
    }
}

The suffix is a mandatory argument. The presetsfile is optional. The presets file is read on plugin startup.