DYNDNS NETCUP GO

Dyndns client for the netcup DNS API written in go. Not related to netcup GmbH. It is heavily inspired by this project which might be also a good solution for your dynamic DNS needs.

Table of Contents

• Features
• Installation
  • Docker compose
  • Docker CLI
  • Environment Variables
    • Manual
    • From source
• Usage
  • Prequisites
  • Run dyndns-netcup-go
    • Commandline flags
  • Cache
• Contributing

Features

• Multi domain support
• Subdomain support
• TTL update support
• Creation of a DNS record if it doesn't already exist
• Multi host support (nice when you need to update both @ and *)
• IPv6 support
• Secure Docker support
• Secret files

If you need additional features please open up an Issue.

Installation

Docker compose example using secret files

You need to create config.yml file in the same directory as the docker-compose.yml file, take a look at config/example.yml for an example. For a Docker setup do not save your secrets (api key, etc.) directly in the config.yml, but rather as environment variable or secret file, as shown below. For secrets management create three files under secrets/ with the names customernr, apikey and apipassword. To further protect the secrets from unauthorized access, make sure it is owned by the user that runs dyndns-netcup-go, by default being the UID 62534 and make it read-only:

mkdir -p secrets/
sudo chown 62534:62534 secrets/*
sudo chmod 440 secrets/*

After that setup you can use the docker-compose.yml as example.

Docker CLI

docker run -d \
    -v $(pwd)/config.yml:/config.yml \
    -e INTERVAL=300 \
    -e CUSTOMERNR=111111 \
    -e APIKEY=my-fancy-api-key \
    -e APIPASSWORD=my-fancy-api-pw \
    ghcr.io/hentra/dyndns-netcup-go

This allows you to store the configuration in plain text(e.g. git) and inject the secrets safely from a secret management solution.

Environment Variables

Environment Variable	Description
INTERVAL	defines the interval of DNS updates in seconds
CUSTOMERNR_FILE	location of the secrets file containing your customer number from netcup
APIKEY_FILE	location of the secrets file containing your API key from netcup
APIPASSWORD_FILE	location of the secrets file containing your API password from netcu
CUSTOMERNR	alternative to secrets file: customer number from netcup
APIKEY	alternative to secrets file: containing your API key from netcup
APIPASSWORD	alternative to secrets file: containing your API password from netcu

Manual

1. Download the lastest binary for your OS
2. cd to the file you downloaded and unzip
3. Put dyndns-netcup-go somewhere in your path

From source

First, install Go as recommended. After that run following commands:

git clone https://github.com/Hentra/dyndns-netcup-go.git 
cd dyndns-netcup-go
go install

This will create a binary named dyndns-netcup-go and install it to your go binary home. Make sure your GOPATH environment variable is set.

Refer to Usage for further information.

Usage

Prequisites

• You need to have a netcup account and a domain, obviously.
• Then you need an apikey and apipassword. Here is a description (in German) on how you get those.

Run dyndns-netcup-go

1. Move/rename the example configuration config/example.yml to config.yml and fill out all the fields. There are some comments in the file for further information.
2. Run dyndns-netcup-go -v in the same directory as your configuration file and it will configure your DNS Records. You can specify the location of the configuration file with the -c or -config flag if you don't want to run it in the same directory. To disable the output for information remove the -v flag. You will still get the output from errors.

It might be necessary to run this program every few minutes. That interval depends on how you configured your TTL.

Commandline flags

For a list of all available command line flags run dyndns-netcup-go -h.

Cache

Without the cache the application would lookup its ip addresses and fetch the DNS records from netcup. After that it will compare the specified hosts in the DNS records with the current ip addresses and update if necessary.

As reported in this issue it would be also possible to store the ip addresses between two runs of the application and only fetch DNS records from netcup when they differ.

To enable the cache configure the two variables IP-CACHE and IP-CACHE-TIMEOUT as according to the comments in example.yml.

Contributing

For any feature requests and or bugs open up an Issue. Feel free to also add a pull request and I will have a look on it.