Route 53 Dynamic DNS with VyOS

1 minute read

The Amazon Web Services team has a great writeup on Medium about how to roll your own dynamic DNS provider using Route 53. Actually, it uses a smattering of AWS offerings beyond just DNS to offload most of the complexity and just require a simple script on the client side.

In this post, we describe how to build your own dynamic DNS system with a small script and several AWS services. There are other systems that provide similar solutions; however, building a serverless system using nothing but AWS services and a few lines of code is simple, cost-effective, and an example of how to build your own serverless solutions on AWS.

Definitely read their writeup if you have even a remote interest in such things, because it’s very well done and explains the whole idea thoroughly.

To jump to the punchline, the client system must run a simple script that does three things:

  1. Gets the current IP address
  2. Builds a URI to update the IP using a shared secret
  3. Performs an HTTP GET on that URI

That’s all that the client has to do. Obviously, for this to be effective over time, it needs to run on a regular basis so that changes to the client’s IP are reflected in DNS in a timely fashion.

Once you’ve copied their update script onto your VyOS router (and ensured the file is executable), set up a scheduled task to run it periodically:

$ configure
# set system task-scheduler task AWS-DDNS executable arguments "your-hostname.dyn.your-domain.com. SHAREDSECRETHERE your-api-endpoint.amazonaws.com/prod"
# set system task-scheduler task AWS-DDNS executable path /path/to/your/script.bash
# set system task-scheduler task AWS-DDNS interval 5m
# commit
# save

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