netcup-api-ddns

A drop dead simple and lightweight Python3 client, that...

• uses Netcups DNS API to use a subdomain for DynDNS
• works with IPv4 and IPv6
• is based on nc_dnsapi from https://github.com/nbuchwitz/nc_dnsapi

Prerequisites

• Python >= 3.11 with pip
• bash, git
• curl (for the default command to determine the external IPv4 / IPv6 addresses )

Installation

• to install for development, run setup_dev_venv.sh
• to run: setup_exec_venv.sh

Usage

• setup your credentials and configuration details in netcup-ddns.conf
• run update_ddns_subdomain.py in a venv with dependencies installed
  • the program can be stopped with kill / SIGTERM / SIGHUP or CTRL-C

Notes / Remarks

• To disable IPv6, set the fetch_ip6_cmd configuration key to an empty value
• Make sure that the TTL in your netcup DNS zone is configured to a reasonable value, otherwise the new records won't be populated in acceptable time
• For quick testing, you could fetch the records directly from the netcup DNS: dig AAAA @root-dns.netcup.net subdomain.yourdomain.tld (omit AAAA for IPv4)
• For practical deployment on a Linux/Unix server or router, it is probably a good idea to:
  • replace the curl commands to fetch external IPs with a local alternative that does not rely on remote machines to determine the external IPs
  • run this Python script with minimal privileges
  • create a proper system service, e.g. systemd unit files on Linux