Updating DNS records based on data received via DynDNS compatible requests from e.g. routers such as AVM Fritzbox
- Support for IPv4, IPv6 and IPv6 LAN Prefix
- IPv4 will result in updated A record
- IPv6 will result in updated AAAA record
- IPv6 LAN Prefix will update all AAAA records defined in an config mapping of FQDN to IPv6 Interface IDs

Limitations:

No support for DNS round robin or the like
No updating a single FQDN across multiple vendors
No cleanup of DNS records
No updating data other than values of DNS records

TODO

docs
tests

Router DynDNS Examples

AVM Fritzbox

Fritzbox DynDNS Settings:

Update-URL: https://192.168.178.10/fqdns/<domain>/dyndns?ip=<ipaddr>&ip=<ip6addr>&ipv6lanprefix=<ip6lanprefix>&dualstack=<dualstack>
Domainname: test1.domain.tld
Username:   testuser
Password:   testpassword

App config:

{
  "fqdns": {
    "test1.domain.tld": {
      "vendor": "...",
      "dyndns_credentials": {
        "testuser": "9f735e0df9a1ddc702bf0a1a7b83033f9f7153a00c29de82cedadc9957289b05"
      }
    }
  }
}

IPv6 LAN Prefix & Interface ID (IID)

Providers will assign an publicly routed IPv6 Prefix for a client. Normally a /48 or /64.

Depending on the clients router configuration, devices behind it will use this prefix to assign themselves a public IPv6.

These devices append an Interface ID (or: host part) to the prefix. How this IID is generated depends on the device configuration.

It may be generated by using its MAC Address, it may be generated randomly for privacy reasons.

This helper supports updating DNS records for IIDs when the IPv6 LAN Prefix changes:

If a DynDNS API call contains an ipv6lanprefix, the FQDN settings of the given fqdn will be used to find other FQDNs to update, e.g.:

{
  "fqdns": {
    "test1.domain.tld": {
      "vendor": "...",
      "dyndns_credentials": {
        "testuser": "9f735e0df9a1ddc702bf0a1a7b83033f9f7153a00c29de82cedadc9957289b05"
      },
      "ipv6_lan_prefix_iid_map": {
        "test2.domain.tld": "::2a0:00ff:111c:1234"
      }
    },
    "test2.domain.tld": {
      "vendor": "..."
    }
  }
}

If for this configuration a DynDNS API call for test1.domain.tld is received, that contains ipv6lanprefix, an AAAA DNS record for test2.domain.tld is ensured.

For the above example: An ipv6lanprefix of 2001:db8:85a3::/48 will result in:

test2.domaintld    AAAA    2001:db8:85a3::2a0:00ff:111c:1234

Caveats

Larger IIDs than a prefix allows will be shortened
- e.g.: An ipv6lanprefix of 2001:db8:85a3:1234::/64 with an IID ::9876:2a0:00ff:111c:1234 will result in an IPv6 address 2001:db8:85a3:1234:2a0:00ff:111c:1234

Vendors

All vendor config is defined under a key vendors and the lowercase name of the vendor, e.g.:

{
  "vendors": {
    "hetzner": {
      "enabled": true,
      ...
    }
  }
}

The following common options are available for every vendor:

Option	Default	Required	Description	Example
enabled	false	false	if this vendor is enabled	true
create_zone_if_missing	false	false	if a zone is created for a FQDN if its missing - otherwise raises an error	true
default_zone_ttl	86400	false	default TTL to set for created zones	7200
default_record_ttl	600	false	default TTL to set for created records - if not defined in individual FQDN settings	300

Hetzner

Additional options:

Option	Default	Required	Description	Example
api_url	'https://dns.hetzner.com/api/v1'	false	Hetzner DNS API URL
api_token		true	default TTL to set for created records - if not defined in individual FQDN settings	'secretapitoken'