netcup-dns 0.5.0

Set DNS records to public IP using netcup DNS API

netcup-dns

Set DNS A/AAAA records to your current external IP address using the netcup DNS API.

Security

The public IP is determined through external services. If these are malicious, they could reply with an attackers IP. If we update our DNS entries to that IP, the attacker could generate valid HTTPS certificates, etc.

To remedy this, we ensure that at least 3 different services are queried and that all report the same external IP.

Installation

Install release from PyPI (https://pypi.org/project/netcup-dns/):

pip install netcup-dns

Install release from TestPyPI (https://test.pypi.org/project/netcup-dns/):

pip install -i https://test.pypi.org/simple/ netcup-dns

Build and install on Arch Linux:

make

Build and install with pip:

make install-pip

Configuration

For each netcup customer, create a .json configuration file inside /etc/netcup-dpns.

There is an example configuration.

Usage

usage: netcup-dns [-h] [--config CFG_FILES [CFG_FILES ...]]
                  [--cache-directory CACHE_DIR]
                  [--cache-validity-seconds CACHE_VALIDITY_SECONDS]

Update DNS A/AAAA records with your current external IP address using the
netcup DNS API.

options:
  -h, --help            show this help message and exit
  --config CFG_FILES [CFG_FILES ...]
                        Path to one or more .json configuration files.
  --cache-directory CACHE_DIR
                        Path to cache directory. Retrieved and updated DNS
                        records are cached there.
  --cache-validity-seconds CACHE_VALIDITY_SECONDS
                        Value in seconds for how long cached DNS records are
                        valid. Set to `0` to disable caching.

Examples

Both examples use the same effective configuration. In the second case, personal information such as the API password is stored in a separate configuration file.

netcup-dns --config ./cfg/example.json
netcup-dns --config ./cfg/public.json ./cfg/secret.json

TODOs

Alternatives:

• https://codeberg.org/anschu/netcup-dyndns-client
• https://codeberg.org/linxside/ncdapi (archived)

API backend:

• Currently: nc-dnsapi
  • https://pypi.org/project/nc-dnsapi/
  • https://github.com/nbuchwitz/nc_dnsapi
• Alternatives:
  • https://github.com/johndoe31415/dnssync_nc

Alternative external IP detection:

def external_ip_upnp():
    """
    https://stackoverflow.com/a/41385033

    Didn't work for me. Even after double checking fritz.box settings:

    fritz.box > Heimnetz > Netzwerk > Statusinformationen über UPnP übertragen
    """
    import miniupnpc
    u = miniupnpc.UPnP()
    u.discoverdelay = 1000
    u.discover()
    u.selectigd()
    print('external ip address: {}'.format(u.externalipaddress()))