deSEC Dynamic DNS Client

A lightweight Bash client for updating deSEC dynamic DNS records. Supports multiple zones with independent configuration and automatic IPv6 address change detection.

Note: This client is IPv6-only. It monitors dynamic IPv6 addresses on specified network interfaces and updates records via update6.dedyn.io. IPv4 is not supported.

Features

• Multi-zone support — manage multiple domains, each with its own configuration file.
• IP change detection — tracks addresses per zone to avoid unnecessary API calls.
• Safe configuration — config files are parsed without shell evaluation; only expected keys are accepted.
• Systemd integration — includes a service unit for background operation.

Requirements

• Bash 4.0+
• curl

Installation

git clone https://github.com/Docmine17/desec.git
cd desec
chmod +x desec.sh

Configuration

Zone configuration files are stored in the zones/ directory. Each file defines a single zone and must use your subdomain + dedyn.io.conf extension.

Creating a zone

Copy the provided sample and edit it:

cp zones/domain.dedyn.io.sample zones/yourdomain.dedyn.io.conf

Each .conf file specifies the network interface, API token, and an optional IP selection mode on a single line separated by spaces:

INTERFACE TOKEN [IP_TYPE]

Supported IP_TYPE values:

• any (default): Uses any valid global IPv6 address available on the interface.
• stable: Uses only stable SLAAC (00) or static (80) addresses.
• temporary: Uses only dynamic privacy extension addresses (01).

Example (zones/yourdomain.dedyn.io.conf):

eth0 your_desec_token_here stable

Use ip -6 addr to identify the correct interface.

Usage

Manual execution

./desec.sh

Options

Option	Description	Default
--zone	Path to the directory containing .conf files.	<script_dir>/zones
--interval	Check interval in seconds.	20
-h, --help	Show usage information.	—

Examples:

# Custom config directory
./desec.sh --zone /etc/desec/zones/

# Check every 60 seconds
./desec.sh --interval 60

# Both options combined
./desec.sh --zone /etc/desec/zones/ --interval 60

Running as a systemd service

1. Edit desec-dns.service and set the correct path in ExecStart:

   ExecStart=/bin/bash /path/to/desec.sh

2. Install and enable the service:

   sudo cp desec-dns.service /etc/systemd/system/
   sudo systemctl daemon-reload
   sudo systemctl enable --now desec-dns.service

3. Check status:

   systemctl status desec-dns.service

How it works

1. The script loads all .conf files from the configured zones directory.
2. For each zone, it reads the current dynamic IPv6 address from the specified interface.
3. If the address differs from the previously recorded one, it sends an update to the deSEC API.
4. The process repeats at the configured interval.

On receiving SIGTERM or SIGINT, the script logs the event and exits cleanly.

License

MIT