ulikoehler / FlareDNS

Cloudflare DynDNS updater client to overcome flexibility limitations of existing clients

FlareDNS

FlareDNS is a Cloudflare DynDNS updater client to overcome flexibility limitations of existing clients

FlareDNS is currently in beta and being tested on some of my systems

It gets the external IP address information from IPify and can update both A and AAAA records simultaneously.

FlareDNS was built specifically for configurations where multiple servers share the same IPv4 address but have separate IPv6 addresses. You can easily run multiple FlareDNS instances to accomodate for multiple DNS updates.

FlareDNS is simple, reliable and transparent. No huge DynDNS code bases to go through if you need to make adjustments - just a single file with not much code, reusable even if you need to do esoteric tasks like

• Update multiple separate AAAA records with IP addresses calculated from the public IP of the host (e.g. virtual servers)
• Query a DHCP lease table for appropriate IP addresses
• Do remote IP
• Configure DynDNS to use backup links if main route is not up While FlareDNS currently doesn't provide any pre-build mechanisms for these tasks, it makes it as easy as possible to implement them.

Note: FlareDNS will only work when you are using the Cloudflare Nameservers for your domain. It's free and it works extremely well - I recommend it. Note the minimum TTL of 2 minutes for Cloudflare DNS (which is not really too much of a limitation in most real-world scenarios).

Prerequisites

• You must setup your domain on Cloudflare and create the appropriate records for the (sub)domain, e.g. dyndns.mydomain.com
• You must create a Cloudflare global API key (domain API token currently doesn't work, pull requests welcome!)
• The system where you want to run FlareDNS must have internet access in order to request the current IP address
• Either Python3 or Docker must be available to run FlareDNS

Install dependencies using

pip3 install -r requirements.txt

How to use (without Docker)

Tell FlareDNS to check & update DNS every 60 seconds using

python3 flaredns.py --email [e-mail] --api-key c6c94fd52184dcc783c5ec1d5089ec354b9d9 --hostname dyndns.mydomain.com --ipv4 --ipv6 --interval 60

Command line help:

$ python flaredns.py --help
usage: flaredns.py [-h] -e EMAIL -k API_KEY -n HOSTNAME [-4] [-6] [-d] [-i INTERVAL]

optional arguments:
  -h, --help            show this help message and exit
  -e EMAIL, --email EMAIL
                        The Cloudflare login email to use
  -k API_KEY, --api-key API_KEY
                        The Cloudflare global API key to use. NOTE: Domain-specific API tokens will NOT work!
  -n HOSTNAME, --hostname HOSTNAME
                        The hostname to update, e.g. mydyndns.mydomain.com
  -4, --ipv4            Update A record with the current IPv4
  -6, --ipv6            Update AAAA record with the current IPv6
  -d, --debug           Additional debug logging
  -i INTERVAL, --interval INTERVAL
                        The update interval in seconds. Set to 0 to only update once. Strictly speaking the sleep time after any update attempt

How to use (with docker)

We provide a prebuilt docker image at Docker Hub. This provides you with the ability to run FlareDNS in a consistent environment without having to install system-level dependencies like Python and the few libraries that FlareDNS requires

docker run -ti --network host --rm --name FlareDNS-dyndns.mydomain.com ulikoehler/flaredns:latest python flaredns.py --email [e-mail] --api-key c6c94fd52184dcc783c5ec1d5089ec354b9d9 --hostname dyndns.mydomain.com --ipv4 --ipv6 --interval 60

Note that --network host is enable IPv6 support on the container if and only if it is enabled on the host.

How to install as a systemd service

In order to autostart, clone FlareDNS into /opt/FlareDNS (you can change this in the .service file)

git clone https://github.com/ulikoehler/FlareDNS.git /opt/FlareDNS

Now we can install the service file:

# Docker variant. Does not have any dependencies.
sudo cp /opt/FlareDNS/examples/UpdateFlareDNSDocker.service /etc/systemd/system/UpdateFlareDNS.service
# "No docker" variant. Requires global "pip install -r requirements.txt"!
sudo cp /opt/FlareDNS/examples/UpdateFlareDNSNoDocker.service /etc/systemd/system/UpdateFlareDNS.service

Don't forget to edit /etc/systemd/system/UpdateFlareDNS.service and set the correct parameters

Now let's enable (i.e. autostart on boot) and start the service

sudo systemctl enable --now UpdateFlareDNS

You can view the logs using

sudo journalctl -xfu UpdateFlareDNS