fritzbox-cloudflare-dyndns

AVM FRITZ!Box Cloudflare DNS-service

This project has some simple goals:

• Offer a slim service without any additional service requirements
• Allow for two different combined strategies: Polling (through FRITZ!Box SOAP-API) and Pushing (FRITZ!Box Custom-DynDns setting).
• Allow multiple domains to be updated with new A (IPv4) and AAAA (IPv6) records
• Push those IP changes directly to CloudFlare DNS
• Deploy in docker compose

If this fits for you, skim over the CNAME workaround if this is a better solution for you, otherwise feel free to visit the appropriate strategy section of this document and find out how to configure it correctly.

CNAME record workaround

Before you try this service evaluate a cheap workaround, as it does not require dedicated hardware to run 24/7:

Have dynamic IP updates by using a CNAME record to your myfritz address, found in Admin > Internet > MyFRITZ-Account. It should look like [hash].myfritz.net.

This basic example of a BIND DNS entry would make intranet.example.com auto update the current IP:

$TTL 60
$ORIGIN example.com.
intranet IN CNAME [hash].myfritz.net

Beware that this will expose your account hash to the outside world and depend on AVMs service availability.

Strategies

FRITZ!Box pushing

You can use this strategy if you have:

• access to the admin panel of the FRITZ!Box router.
• this services runs on a public interface towards the router.

In your .env file or your system environment variables you can be configured:

Now configure the FRITZ!Box router to push IP changes towards this service. Log into the admin panel and go to Internet > Shares > DynDNS tab and setup a Custom provider:

If you specified credentials you need to append them as additional GET parameters into the Update-URL like &username=<user>&password=<pass>.

FRITZ!Box polling

You can use this strategy if you have:

• no access to the admin panel of the FRITZ!Box router.
• for whatever reasons the router can not push towards this service, but we can poll from it.
• you do not trust pushing

In your .env file or your system environment variables you can be configured:

You can try the endpoint URL in the browser to make sure you have the correct port, you should receive an 404 ERR_NOT_FOUND.

Because FRITZBOX_ENDPOINT_URL is set by default on the docker image, you have to explicitly set it to an empty string to disable polling

Cloudflare setup

To get your API Token do the following: Login to the cloudflare dashboard, go to My Profile > API Tokens > Create Token > Edit zone DNS, give to token some good name (e.g. "DDNS"), add all zones that the DDNS should be used for, click Continue to summary and Create token. Be sure to copy the token and add it to the config, you won't be able to see it again.

In your .env file or your system environment variables you can be configured:

This service allows to update multiple records, an advanced example would be:

CLOUDFLARE_ZONES_IPV4=ipv4.example.com,ip.example.com,server-01.dev.local
CLOUDFLARE_ZONES_IPV6=ipv6.example.com,ip.example.com,server-01.dev.local

Considering the example call http://192.168.0.2:8080/ip?v4=127.0.0.1&v6=::1 every IPv4 listed zone would be updated to 127.0.0.1 and every IPv6 listed one to ::1.

Register IPv6 for another device (port-forwarding)

IPv6 port-forwarding works differently and so if you want to use it you have to add the following configuration.

Warning: FRITZBOX_ENDPOINT_URL has to be set for this to work.

To access a device via IPv6 you need to add it's global IPv6 address to cloudflare, for this to be calculated you need to find out the local part of it's IP. You can find out the local part of a device's IP, by going to the device's settings and looking at the IPv6 Interface-ID. It should look something like this: ::1234:5678:90ab:cdef. Sometimes the FritzBox seems to use a subnet, so you might need to add change it from something like ::1234:5678:90ab:cdef to ::1:1234:5678:90ab:cdef

Docker compose setup

Here is an example docker-compose.yml with all features activated:

version: '3.7'

services:
  updater:
    image: ghcr.io/cromefire/fritzbox-cloudflare-dyndns:1
    network_mode: host
    # build:
    #   context: .
    environment:
      - FRITZBOX_ENDPOINT_URL=http://fritz.box:49000
      - FRITZBOX_ENDPOINT_TIMEOUT=30s
      - FRITZBOX_ENDPOINT_INTERVAL=3s
      - CLOUDFLARE_API_EMAIL=max@example.com
      - CLOUDFLARE_API_KEY=demo
      - CLOUDFLARE_ZONES_IPV4=test.example.com
      - CLOUDFLARE_ZONES_IPV6=test.example.com

Now we could configure the FRITZ!Box to http://[docker-host-ip]:49000/ip?v4=<ipaddr>&v6=<ip6addr>&prefix=<ip6lanprefix> and it should trigger the update process.

Docker build

Note: A pre-built docker image is also available on this GitHub repository.

More raw approach would be to build and run it yourself:

docker build -t fritzbox-cloudflare-dyndns .
docker run --rm -it -p 8888:8080 fritzbox-cloudflare-dyndns

If you leave CLOUDFLARE_* unconfigured, pushing to CloudFlare will be disabled for testing purposes, so try to trigger it by calling http://127.0.0.1:8888/ip?v4=127.0.0.1&v6=::1 and review the logs.