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CloudFlare DDNS via CF Worker

This repository brings several improvement to this project.

Feature

  • Auto create DNS record when missing
  • IPv6 support (rudimentry)
  • Allow the record to be specified by the user
  • Multiple user support with allowed subdomain matching, and HMAC authentication

Usage

The worker script requires Node.JS and WebPack to function.

Before starting, you need to create a new API Token on your Cloudflare's profile page with permissions to edit the DNS records of one of your domains (Permission Zone.DNS.Edit).

Worker

You need to create a JSON file for authentication and authorization with the format:

[
    {
        "id": "<id for the token>",
        "token": "<any random long string>",
        "allowed": "<allowed subdomain>"
    }
]

The allowed parameter supports wildcard (as described in the wildcard-match package). The root domain should be included in the parameter. Here's a working example:

[
    {
        "id": "charlie",
        "token": "+xM1Uz56ZX7mpVaDJcX49w==",
        "allowed": "*.charlie.partner.example.com"
    }
]

which will allow updating all subdomains on charlie.partner.example.com.

Next, you need to minify the JSON and Base64-encode it. Then you need to get the Zone ID for your site (a long hex string available in the "Overview" page in your site, at the right sidebar).

Use Wrangler to create a new worker and clone the project in, set src/index.js as the main file. Set those environment variables:

  • CF_API_TOKEN: As described above, your CF API Token with Zone.DNS.Edit permission to the specified zone. Use wrangler secret put to set this variable!
  • ZONE_ID: The hex Zone ID. You can put this in the wrangler.toml.
  • AUTH: The Base64-encoded JSON string containing auth data. Use wrangler secret put to set this variable!

Then publish the worker.

Agent

A PowerShell agent is provided in the 'agent' directory. Edit the config.ps1 for configuration and run it with a scheduled task. PowerShell 7 or higher is required.

To write your own agent, you need to send the following payload to the worker route:

{
    "id": "<hmac token id>",
    "domain": "<full domain>",
    "addr": "<addr, null for auto>",
    "type": "<ipv4 or ipv6>",
    "timestamp": "<unix_timestamp>"
}

The request must be made no longer than 5 minutes after the timestamp, and the whole request body must be signed using the HMAC token, with HMAC-SHA-256 algorithm. The signature is Base64-encoded and placed into the Authorization HTTP header.