DynDNS is a simple Linux client to update one or more of your dynamic DNS hosting services with the hosts public IPv4 and/or IPv6 addresses. Just configure your own update URLs in the configuration file and run it.

DynDNS supports dynamic DNS services which use a simple http or https URL get update mechanism, such as:

• Duck DNS
• Dynv6
• Dynu
• FreeDNS

The above all offer free dynamic DNS services. There is example configuration for each of these services in the sample dyndns.toml configuration file but note that most (free or paid) dynamic DNS services should be supported. Extensive configuration instructions are provided in that file.

Why another dynamic DNS client? I wanted a simple, lightweight app managed by systemd, generic and flexible enough to use with any dynamic DNS service and IP address servers. It should work with both IPv4 and IPv6 and allow multiple URLs to be set. I didn't find anything I liked so wrote my own.

Ensure you read the latest documentation and the instructions in the example dyndns.toml file but then ask a question on the DynDNS discussion forum if you still need clarification about usage or operation.

This client runs every poll_period (default 10 mins) and determines your current public IPv4 and/or IPv6 address from a list of configured public address servers. If any IP address differs from the last address then an update is sent to the pertinent configured dynamic DNS URLs. You can configure "<ipv4>" and/or "<ipv6>" placemarkers in your URLs to be substituted at runtime, and/or for those services that support it, rely on automatic IP detection. Every force_period (default 24 hours), an update is sent regardless to each service. The last IP addresses determined are stored on change only and are always cached to disk so they are preserved through reboots. The service URLs, their parameters to update, the time periods, and the list of IP address servers can be changed in the configuration file.

You copy the sample dyndns.toml file to your ~/.config/ and then edit it for your requirements. Follow the examples and instructions in that file.

Requires python 3.7 or later and a modern Linux systemd environment.

1. Clone repository and create configuration:

   $ git clone https://github.com/bulletmark/dyndns.git
   $ cd dyndns
   $ mkdir -p ~/.config
   $ cp dyndns.toml ~/.config
   $ vim ~/.config/dyndns.toml # Add your [[urls]] entries

2. Create virtual environment (venv) and install service.

   $ python3 -m venv .venv
   $ .venv/bin/pip install -r requirements.txt
   $ sudo cp dyndns.service /etc/systemd/system
   $ sudoedit /etc/systemd/system/dyndns.service # Edit #TEMPLATE# values.

Note: Alternatively, to create the venv, install the requirement packages, insert the template values, and enable + start the service you can use my pinstall tool. Just install it and do the following in the dyndns directory.

$ pinstall venv
$ pinstall service

To enable starting at boot and also start immediately:

$ sudo systemctl enable dyndns
$ sudo systemctl start dyndns

To stop immediately and also disable starting at boot:

$ sudo systemctl stop dyndns
$ sudo systemctl disable dyndns

Show status:

$ systemctl status dyndns

Show log:

$ journalctl -u dyndns

cd to source dir, as above. Then update the source:

$ git pull

Update ~/.config/dyndns.toml and /etc/systemd/system/dyndns.service if necessary. Then restart the service.

$ sudo systemctl restart dyndns

Type dyndns -h to view the usage summary:

usage: dyndns [-h] [-v] [-i] [-c CONF]

Update external IP v4 and/or v6 addresses to a dynamic DNS server.

options:
  -h, --help            show this help message and exit
  -v, --verbose         verbose output
  -i, --ignore-cache    ignore cache for startup
  -c CONF, --conf CONF  configuration file, default =
                        ~/.config/dyndns.toml

• Added the ability to cater for IPv6 addresses.

• Added the ability to configure multiple dynamic DNS server URLs instead of just one and also the ability to substitute "<ipv4>" and "<ipv6>" placemarkers in the url string.

• Cater for dynamic DNS servers which return one or more text strings for success/failure instead of just looking at the HTML response status code.

• Changed from YAML to TOML configuration file format as that is the future for Python apps given TOML is now included in the standard packages since Python v3.11. Note that tomli package gets installed if you are running on < 3.11. This change mean any previous personal configuration file must be ported to the new format.

• Requires minimum Python version 3.7 instead of 3.6.

Copyright (C) 2017 Mark Blakeney. This program is distributed under the terms of the GNU General Public License. This program is free software: you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation, either version 3 of the License, or any later version. This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License at http://www.gnu.org/licenses/ for more details.