ddns-updater

A Hurricane Electric dynamic DNS record updater, designed to be run as a service on Linux, with example SystemD unit files provided.

This implementation has checks to not try to update a record if it's currently the same address; this reduces the traffic to the DDNS service. The default endpoint for this is ifconfig.me, but any service which returns a plaintext body in an HTTP response that only contains the requesting client's IP address will work.

Configuration format

Configuration files should be TOML files with records stored in the following format:

[comment]
host = "host-name"
key = "secret-key"
interface = "enp3s0"
record_type = "A"

All comments should be unique, and should not contain periods. Technically in TOML, what we're using as a comment is actually a key in the overall key-value tree, and this results in some unfortunate emergent behaviors.

Deploying

Build then install the binary:

$ cargo build --release
$ sudo cp target/release/ddns-updater /usr/bin/local/ddns-updater

The included .service file requires an edit to define the user the script will run under, and then both it and the .timer file should be installed in /etc/systemd/system/. Then, with a few systemctl calls, you can set up the updater to run automatically on the hour:

# systemctl enable ddns-updater.timer
# systemctl start ddns-updater.timer
$ systemctl status ddns-updater

Finally, build your configuration file like the files in the data directory, and install them either in /srv/ddns, the default location for the script, or in your location of choice.

Future plans

• Support for more record types. The default will remain A records, with reasonable defaults for any additional fields so existing configuration files will continue to work.
• Support for more endpoints. I use HE for my DNS, so it's what I test the most, but other endpoints with the same API should work fine.
• Support for listening for IP changes? This seems to be a very open-ended question right now.