dnscontrol/docs/_providers/axfrddns.md

name	title	layout	jsId
AXFRDDNS	AXFR+DDNS Provider	default	AXFRDDNS

AXFR+DDNS Provider

This provider uses the native DNS protocols. It uses the AXFR (RFC5936, Zone Transfer Protocol) to retrieve the existing records and DDNS (RFC2136, Dynamic Update) to make corrections. It can use TSIG (RFC2845) or IP-based authentication (ACLs).

It is able to work with any standards-compliant authoritative DNS server. It has been tested with BIND, Knot, and Yadifa.

Configuration

Authentication

Authentication information is included in the creds.json entry for the provider:

• transfer-key: If this exists, the value is used to authenticate AXFR transfers.
• update-key: If this exists, the value is used to authenticate DDNS updates.

For instance, your creds.json might looks like:

{% highlight json %} { "axfrddns": { "transfer-key": "hmac-sha256:transfer-key-id:Base64EncodedSecret=", "update-key": "hmac-sha256:update-key-id:AnotherSecret=" } } {% endhighlight %}

If either key is missing, DNSControl defaults to IP-based ACL authentication for that function. Including both keys is the most secure option. Omitting both keys defaults to IP-based ACLs for all operations, which is the least secure option.

If distinct zones require distinct keys, you will need to instantiate the provider once for each key:

{% highlight javascript %} var AXFRDDNS_A = NewDnsProvider('axfrddns-a', 'AXFRDDNS'} var AXFRDDNS_B = NewDnsProvider('axfrddns-b', 'AXFRDDNS'} {% endhighlight %}

And update creds.json accordingly:

{% highlight json %} { "axfrddns-a": { "transfer-key": "hmac-sha256:transfer-key-id:Base64EncodedSecret=", "update-key": "hmac-sha256:update-key-id:AnotherSecret=" }, "axfrddns-b": { "transfer-key": "hmac-sha512:transfer-key-id-B:SmallSecret=", "update-key": "hmac-sha512:update-key-id-B:YetAnotherSecret=" } } {% endhighlight %}

Default nameservers

The AXFR+DDNS provider can be configured with a list of default nameservers. They will be added to all the zones handled by the provider.

This list can be provided either as metadata or in creds.json. Only the later allows get-zones to work properly.

{% highlight javascript %} var AXFRDDNS = NewDnsProvider('axfrddns', 'AXFRDDNS', 'default_ns': [ 'ns1.example.tld.', 'ns2.example.tld.', 'ns3.example.tld.', 'ns4.example.tld.' ] } {% endhighlight %}

{% highlight json %} { nameservers = "ns1.example.tld,ns2.example.tld,ns3.example.tld,ns4.example.tld" } {% endhighlight %}

Primary master

By default, the AXFR+DDNS provider will send the AXFR requests and the DDNS updates to the first nameserver of the zone, usually known as the "primary master". Typically, this is the first of the default nameservers. Though, on some networks, the primary master is a private node, hidden behind slaves, and it does not appear in the NS records of the zone. In that case, the IP or the name of the primary server must be provided in creds.json. With this option, a non-standard port might be used.

{% highlight json %} { master = "10.20.30.40:5353" } {% endhighlight %}

When no nameserver appears in the zone, and no default nameservers nor custom master are configured, the AXFR+DDNS provider will fail with the following error message:

{% highlight text %} [Error] AXFRDDNS: the nameservers list cannot be empty. Please consider adding default nameservers or an explicit master in creds.json. {% endhighlight %}

Server configuration examples

Bind9

Here is a sample named.conf example for an authauritative server on zone example.tld. It uses a simple IP-based ACL for the AXFR transfer and a conjunction of TSIG and IP-based ACL for the updates.

{% highlight javascript %} options {

listen-on { any; };
listen-on-v6 { any; };

allow-query { any; };
allow-notify { none; };
allow-recursion { none; };
allow-transfer { none; };
allow-update { none; };
allow-query-cache { none; };

};

zone "example.tld" { type master; file "/etc/bind/db.example.tld"; allow-transfer { example-transfer; }; allow-update { example-update; }; };

Allow transfer to anyone on our private network

acl example-transfer { 172.17.0.0/16; };

Allow update only from authenticated client on our private network

acl example-update { ! { !172.17.0.0/16; any; }; key update-key-id; };

key update-key-id { algorithm HMAC-SHA256; secret "AnotherSecret="; }; {% endhighlight %}

FYI: get-zones

When using get-zones, a custom master or a list of default nameservers should be configured in creds.json.

THe AXFR+DDNS provider does not display DNSSec records. But, if any DNSSec records is found in the zone, it will replace all of them with a single placeholder record:

{% highlight text %} __dnssec IN TXT "Domain has DNSSec records, not displayed here." {% endhighlight %}

FYI: create-domain

The AXFR+DDNS provider is not able to create domain.

FYI: AUTODNSSEC

The AXFR+DDNS provider is not able to ask the DNS server to sign the zone. But, it is able to check whether the server seems to do so or not.

When AutoDNSSEC is set, the AXFR+DDNS provider will emit a warning when no RRSIG, DNSKEY or NSEC records are found in the zone.

When AutoDNSSEC is not set, the AXFR+DDNS provider will emit a warning when RRSIG, DNSKEY or NSEC records are found in the zone.