netcup DNS Authenticator plugin for Certbot

pip install certbot-dns-netcup==1.4.3



Version License: Apache Docker image size

netcup DNS Authenticator plugin for certbot.

This plugin automates the process of completing a dns-01 challenge by creating, and subsequently removing, TXT records using the netcup CCP API via lexicon.

Note: This manual assumes certbot ≥ v1.7, which has improved the naming scheme for external plugins. If you cannot upgrade, please also refer to the Old option naming scheme section below.


Since this package acts as a plugin for certbot, the installation method can vary depending on how certbot is installed.


If certbot is installed normally as a python package, the plugin can be installed using:

pip install certbot-dns-netcup


If certbot is installed as a snap, you'll have to install this plugin as follows:

sudo snap install certbot-dns-netcup

Furthermore, the following seems to be required in order to connect the plugin to certbot:

sudo snap set certbot trust-plugin-with-root=ok
sudo snap connect certbot:plugin certbot-dns-netcup


Using docker, you can pull an image that contains both certbot and a matching version of the plugin:

docker pull coldfix/certbot-dns-netcup


To acquire a single certificate for both example.com and *.example.com, waiting 1200 seconds (20min) for DNS propagation:

certbot certonly \\
  --authenticator dns-netcup \\
  --dns-netcup-credentials ~/.secrets/certbot/netcup.ini \\
  --dns-netcup-propagation-seconds 1200 \\
  --keep-until-expiring --non-interactive --expand \
  --server https://acme-v02.api.letsencrypt.org/directory \
  -d 'example.com' \\
  -d '*.example.com'

The parameters and the format of the credentials file are described below.

Named Arguments

To start using DNS authentication for netcup, pass the following arguments on certbot's command line:

--authenticator dns-netcup select the authenticator plugin (Required)
--dns-netcup-credentials FILE netcup credentials INI file. (Required)
--dns-netcup-propagation-seconds NUM
waiting time for DNS to propagate before asking
the ACME server to verify the DNS record.
(Default: 900, Recommended: >= 600)

NOTE: You may need to set an unexpectedly high propagation time (≥ 900 seconds) to give the netcup DNS time to propagate the entries! This may be annoying when calling certbot manually but should not be a problem in automated setups. In exceptional cases, 20 minutes may be required. See #28.


Use of this plugin requires a configuration file containing netcup API credentials, obtained from your netcup account page. See also the CCP API documentation.

An example credentials.ini file:

dns_netcup_customer_id  = 123456
dns_netcup_api_key      = 0123456789abcdef0123456789abcdef01234567
dns_netcup_api_password = abcdef0123456789abcdef01234567abcdef0123

The path to this file can be provided interactively or using the --dns-netcup-credentials command-line argument. Certbot records the path to this file for use during renewal, but does not store the file's contents.

CAUTION: You should protect these API credentials as you would the password to your netcup account. Users who can read this file can use these credentials to issue arbitrary API calls on your behalf. Users who can cause Certbot to run using these credentials can complete a dns-01 challenge to acquire new certificates or revoke existing certificates for associated domains, even if those domains aren't being managed by this server.

Certbot will emit a warning if it detects that the credentials file can be accessed by other users on your system. The warning reads "Unsafe permissions on credentials configuration file", followed by the path to the credentials file. This warning will be emitted each time Certbot uses the credentials file, including for renewal, and cannot be silenced except by addressing the issue (e.g., by using a command like chmod 600 to restrict access to the file).


You can pull the latest version of the docker image directly from Docker Hub as follows:

docker pull coldfix/certbot-dns-netcup

Alternatively, the docker image can be built from a local checkout and the included Dockerfile as follows:

docker build -t coldfix/certbot-dns-netcup .

Once that's finished, the application can be run as follows:

docker run --rm \
  -v /var/lib/letsencrypt:/var/lib/letsencrypt \
  -v /etc/letsencrypt:/etc/letsencrypt \
  --cap-drop=all \
  coldfix/certbot-dns-netcup certbot certonly \
    --authenticator dns-netcup \
    --dns-netcup-propagation-seconds 900 \
    --dns-netcup-credentials /var/lib/letsencrypt/netcup_credentials.ini \
    --keep-until-expiring --non-interactive --expand \
    --server https://acme-v02.api.letsencrypt.org/directory \
    --agree-tos --email "webmaster@example.com" \
    -d example.com -d '*.example.com'

You may want to change the volumes /var/lib/letsencrypt and /etc/letsencrypt to local directories where the certificates and configuration should be stored.

Old option naming scheme

It is recommended to use the newest certbot version, at least v1.7.

If you're using a certbot version below v1.7 all options related to external plugins (such as this one) must be prefixed by the name of the plugin. This means that every occurence of dns-netcup in the command line options must be replaced by certbot-dns-netcup:dns-netcup, i.e.:

--authenticator certbot-dns-netcup:dns-netcup

Further, every occurence of dns_netcup in the config file must be prefixed by certbot_dns_netcup:, resulting in a file like this:

certbot_dns_netcup:dns_netcup_customer_id  = ...
certbot_dns_netcup:dns_netcup_api_key      = ...
certbot_dns_netcup:dns_netcup_api_password = ...