fritzbox-cloudflare-dyndns-nginx-lua

Simple FRITZ!Box self-hosted proxy for updating Cloudflare DNS records which runs exclusively in nginx with LuaJIT support.

Requirements

• FRITZ!Box with DynDNS enabled and configured
• Cloudflare API Token with Zone Edit permission
• nginx with LuaJIT support
  • lua-resty-core (required by LuaJIT)
  • lua-resty-lrucache (required by LuaJIT)
  • lua-resty-http
  • lua-cjson

Setup

Cloudflare API Token

Create Cloudflare API Token with Zone Edit permissions (Zone.DNS.Edit) for the specific zone. Write down the token.

nginx

• Clone repository

$ git clone git@github.com:gringus/fritzbox-cloudflare-dyndns-nginx-lua.git

• Copy lua,dyndns.conf and cf-token.conf to nginx configuration directory

# cp -r lua dyndns.conf cf-token.conf /etc/nginx

• Update cf-token.conf

Edit cf-token.conf file by updating the token value obtained in Cloudflare API Token step. Make sure file is protected:

# chmod 0400 /etc/nginx/cf-token.conf

• Create authentication file

Select username and password (some_username and some_password in the example) for endpoint authentication.

# echo -n "some_username:$(openssl passwd -1 'some_password')" > /etc/nginx/dyndns.auth

Make sure file is protected and readable at runtime:

# chmod 0440 /etc/nginx/dyndns.auth
# chgrp nginx /etc/nginx/dyndns.auth

• Add endpoint configuration

Either copy and paste snippet from dyndns.conf file or include it in nginx.conf eg.

include dyndns.conf;

FRITZ!Box

Enable DynDNS (Internet -> Permit Access -> DynDNS -> Use DynDNS) and configure:

• Update URL

URL to self hosted instance including endpoint path (/dyndns by default) eg. https://example.com/dyndns?hostname=<domain>&ipv4=<ipaddr>&ipv6=<ip6lanprefix>&ipv6offset=::1 Supported endpoint parameters:

Parameter	Example	Description
hostname	<domain>	FQDN of existing DNS record to update. No new records get created.
ipv4	<ipaddr>	The value of A record
ipv6	<ip6addr> or <ip6lanprefix>	The value of AAAA record
ipv6offset	::1	Optional ipv6 offset (eg. when <ip6lanprefix> used as value) in IPv6 address notation. The final value of AAAA record will be a sum of ipv6 and ipv6pffset parameters eg. 2001:1234:: and ::ff0 will give 2001:1234::ff0

• Domand name

FQDN which FRITZ!Box will use to watch for DNS changes. It seems FRITZ!Box will query Update URL only when Domain name A record value is different than IPv4 address obtained from ISP.

• Username

Username used when querying Update URL. This should match username in nginx authentication file created in nginx step.

• Password

Password used when querying Update URL. This should match password in nginx authentication file created in nginx step.