Dynamic DNS in Go

This package allows you to set up a dynamic DNS service, which allows you to connect to devices at home from anywhere in the world. It's aim is to be be as cheap as posible, so you'll only need a domain and google's cloud functions or a cheap VPS.

Installation

You can either take the image from DockerHub or build it on your own.

DNS integration

nsupdate - No configuration needed here
Google's Cloud DNS - you need to configure the project name, and the path to your service credentials file.
This could be done through the environment variables:

GCP_PROJECT=.... # Your project name
GOOGLE_APPLICATION_CREDENTIALS=./keys.json # The path to your service credentials.

Using google cloud functions

This project offers an http endpoint that can be used as a cloud function. With that you can easily deploy your dynamic DNS in google's cloud functions. The exported function is: GoDDns
You can deploy it with google's cloud build(look at cloudbuild.yaml) or manually by uploading the source code and defining your function.

Make sure you configure your function's environment variables. Here is an example configuration:

API_KEY=keepThisSecret
ZONE=myzone # the name of your dns zone
DOMAIN=my-domain-to-manage.com # the domain you want to manage, this is optional
TTL=300 # default ttl
PROVIDER=google # this is required
VERBOSE=true # if you want more logs
GCP_PROJECT=my-google-project-name

Using DockerHub

Just customize this to your needs and run:

docker run -it -d \
    -p 8080:8080 \
    -p 53:53 \
    -p 53:53/udp \
    -e SHARED_SECRET=changeme \
    -e ZONE=example.org \
    -e RECORD_TTL=3600 \
    --name=dyndns \
    sp0x/go-ddns:latest

If you want to persist DNS configuration across container runs, add -v /somefolder:/var/cache/bind. If you are experiencing any issues updating DNS configuration using the API (NOTAUTH and SERVFAIL), make sure to add writing permissions for root (UID=0) to your persistent storage (e.g. chmod -R a+w /somefolder).

You can also use Compose / Swarm to set up this project. For more information and an example docker-compose.yml with persistent data storage, please refer to this file: https://github.com/dprandzioch/docker-ddns/blob/master/docker-compose.yml

Build from source / GitHub

git clone https://github.com/dprandzioch/docker-ddns
git checkout master # Make sure to build the latest stable release
cd docker-ddns
$EDITOR envfile
make deploy

Make sure to change all environment variables in envfile to match your needs. Some more information can be found here: https://www.davd.eu/build-your-own-dynamic-dns-in-5-minutes/

Exposed ports

Afterwards you have a running docker container that exposes three ports:

• 53/TCP -> DNS
• 53/UDP -> DNS
• 8080/TCP -> Management REST API

Using the API

That package features a simple REST API written in Go, that provides a simple interface, that almost any router that supports Custom DDNS providers can attach to (e.g. Fritz!Box). It is highly recommended to put a reverse proxy before the API.
For examples of API requests, see the API.http file.

Fields

• secret: The shared secret set in envfile
• domain: The subdomain to your configured domain, in this example it would result in foo.example.org. Could also be multiple domains that should be redirected to the same domain separated by comma, so "foo,bar"
• addr: IPv4 or IPv6 address of the name record

For the DynDNS compatible fields please see Dyn's documentation here:

https://help.dyn.com/remote-access-api/perform-update/

DynDNS compatible API

This package contains a DynDNS compatible handler for convenience and for use cases where clients cannot be modified to use the JSON responses and/or URL scheme outlined above.

This has been tested with a number of routers. Just point the router to your DDNS domain for updates.

The handlers will listen on:

• /nic/update
• /v2/update
• /v3/update

The username is not validated at all so you can use anything as a username Password is the shared secret provided as an ENV variable

Examples

Using a simple crontab script

You can add the file scripts/goddns.sh as a crontab job. This would make requests to the API to update your DNS.
Make sure to have these environment variables:

• ENDPOINT
• API_KEY
• SUBDOMAIN

ddclient example

An example on the ddclient (Linux DDNS client) based Ubiquiti router line:

set service dns dynamic interface eth0 service dyndns host-name set service dns dynamic interface eth0 service dyndns login set service dns dynamic interface eth0 service dyndns password set service dns dynamic interface eth0 service dyndns protocol dyndns2 set service dns dynamic interface eth0 service dyndns server

Optional if you used this behind an HTTPS reverse proxy like I do:

set service dns dynamic interface eth0 service dyndns options ssl=true

This also means that DDCLIENT works out of the box and Linux based devices should work.

D-Link DIR-842:

Another router that has been tested is from the D-Link router line where you need to fill the details in on the Web Interface. The values are self-explanatory. Under the server (once you chosen Manual) you need to enter you DDNS server's hostname or IP. The protocol used by the router will be the dyndns2 by default and cannot be changed.

DNS setup

To provide a little help... To your "real" domain, like domain.tld, you should add a subdomain that is delegated to this DDNS server like this:

dyndns                   IN NS      ns
ns                       IN A       <put ipv4 of dns server here>
ns                       IN AAAA    <optional, put ipv6 of dns server here>

Your management API should then also be accessible through

http://ns.domain.tld:8080/update?...

If you provide foo as a domain when using the REST API, the resulting domain will then be foo.dyndns.domain.tld.

Common pitfalls

• If you're on a systemd-based distribution, the process systemd-resolved might occupy the DNS port 53. Therefore, starting the container might fail. To fix this, disable the DNSStubListener by adding DNSStubListener=no to /etc/systemd/resolved.conf and restart the service using sudo systemctl restart systemd-resolved.service but be aware of the implications... Read more here: https://www.freedesktop.org/software/systemd/man/systemd-resolved.service.html and dstapp/docker-ddns#5