DynDNS Server for Google Cloud DNS

This is a simple DynDNS server that updates a Google Cloud DNS record with the client's IP address. It is designed to be run as a small docker container on a server that has a static IP address.

Usage

1. Clone this repository
2. Build the docker image: docker build -t dyndns:latest .
3. Show the help: docker run --rm dyndns:latest --help

Usage of /dyndns.bin:
  -auth string
        Basic Auth username:password
  -auth-file string
        Path to file containing the Google Cloud credentials (default "google.json")
  -bind-address string
        Bind address for the server (default ":8080")
  -dns-zone-name string
        DNS zone name
  -domain-name string
        Domain name
  -project-id string
        Google Cloud project ID

4. Create a Google Cloud service account and download the JSON key file. It needs read/write permission for the DNS zone you want to update.

Parameters

Parameter	Description	Required
auth	Basic Auth username:password. Use format username:password	No - default env:DYNDNS_AUTH
auth-file	Path to the Google Cloud credentials file	No - default env:DYNDNS_AUTH_FILE => fallback to: google.json
bind-address	Bind address for the server. Use format ip:port	No - default :8080
dns-zone-name	DNS zone name from Cloud DNS	Yes - default: env:DYNDNS_DNS_ZONE_NAME
domain-name	Domain name to update including the subdomain. For example home.mydomain.tld	Yes - default: env:DYNDNS_DOMAIN_NAME
project-id	Google Cloud project ID	Yes - default: env:DYNDNS_PROJECT_ID

When using docker you should not change the --bind-address flag. The container will only expose port 8080.

You can load the auth-file from an env variable. Todo this set --auth-file to env://YOUR_ENV_VAR_NAME and set YOUR_ENV_VAR_NAME to the content of the file.

Run the server

docker run -d --name dyndns \
  -p 8080:8080 \
  -v /path/to/google.json:/google.json \
  dyndns:latest \
  -auth username:password \
  -dns-zone-name my-dns-zone \
  -domain-name home.mydomain.tld \
  -project-id my-google-project

Update the DNS record

This server supports updates of IPv4 and IPv6 addresses. The client can send a GET request to the server.

GET https://my-dyndns-server.lan/dyn?ip_address=IP_V4_ADDRESS&ipv6_address=IP_V6_ADDRESS

The server will validate the provided IP addresses and create/update the DNS records if they are valid.

Example Response

{
  "name": "home.mydomain.tld.",
  "v4": {
    "rr_type": "A",
    "success": true,
    "created": false,
    "updated": true,
    "value": "20.15.79.10"
  },
  "v6": {
    "rr_type": "AAAA",
    "success": true,
    "created": false,
    "updated": true,
    "value": "2a05:3100:0000:572:cafe:f00a:af39:beef"
  }
}

If validation fails or the record could not be updated, the response will contain an error message.

You can only use public routable IP addresses. The server will not accept private or otherwise reserved IP addresses.

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Run without docker

You can also run the server without docker. You need to have Go installed on your system.

1. Clone this repository

2. Build the server:

   • Linux/Mac: go build -o dyndns.bin cmd/server/main.go
   • Windows: go build -o dyndns.exe cmd/server/main.go

Run the server: ./dyndns.(bin|exe) --bind-address="localhost:3000" --auth username:password --dns-zone-name my-dns-zone --domain-name home.mydomain.tld --project-id my-google-project

This will start the server on localhost:3000 with basic auth and the provided Google Cloud credentials.

Client

You can use the provided dyndns-client to update the DNS record. It is a simple Go program that sends a GET request to the server.

Build the client

1. Clone this repository

2. Build the client:

   • Linux/Mac: go build -o dyndns-client.bin cmd/client/main.go
   • Windows: go build -o dyndns-client.exe cmd/client/main.go

Run the client

./dyndns-client.(bin|exe) -- --server-url="https://my-dyndns-server.lan" --username=username --password=password --ip-provider=icanhazipcom

List of available IP providers

./dyndns-client.(bin|exe) --list-providers