dyn-dns-easy

easy dynamic dns built on AWS

Architecture

Lambda, DynamoDB, Route53

How to use

Prereq: aws profile configured for sso login. if not yet done, follow this guide.

create a .env file in the project root directory with the following content:

AWS_PROFILE=YOUR_AWS_PROFILE_NAME_CONFIGURED_IN_YOUR_AWS_CONFIG
AWS_REGION=THE_REGION_YOU_WANT_TO_DEPLOY_TO
AWS_HOSTED_ZONE_IDS=COMMA_SEPARATED_LIST_OF_THE_IDS_OF_YOUR_HOSTED_ZONE_IDS

1. install all deps

npm ci

2. set env and login

source set_env
aws sso login

3. build it

npm run build

4. deploy

npm run deploy

How to use

1. create entry in DynamoDB in the following format:
   • make sure the used zone id was provided to the env key when deploying, otherwise add it and deploy again
   • it is up to you how long the ttl should be, depending on how often you want to call the api
   • generate a secret key and use it in the request to update the record

{
  "hostname": { "S": "my-host-name.ch" },
  "zoneId": { "S": "your-zone-for-your-domain" },
  "recordTtl": { "N": "172800" },
  "secret": { "S": "a-very-secret-key" }
}

2. after deploying you can execute the following command to get the api endpoint.
   the command writes the outputs.json file which contains the api endpoint variable

./get-stack-outputs

3. on the given endpoint you can now update the ip address of the record by sending a post request
   • first get your public ip (e.g. by calling the api (see apiFnUrl in outputs.json)
   • store the current timestamp (seconds since epoch) in a variable
   • then calculate the hash (sha256 hex) of ipAddress + hostname + tiemstamp + secret (joined without any special characters)
   • finally send the following json to the endpoint

{
  "ddns_hostname": "my-host-name.ch",
  "validation_hash": "the-calculated-hash",
  "timestamp": 1736598400
}

you can use the provided update-dns-record script to automate this process
just set the env variables SECRET, HOSTNAME and API_URL and run the script
you can also use the Dockerfile to create an image and run it as a container