A dyndns provider in a CloudFlare worker

With me using CloudFlare and CloudFlare providing free workers, why would I bother with shady dyndns providers, it should be simple enough to implement myself.

This is what I came up with.

Setup

You need wrangler to set this up.

You'll also need to create a few secrets (wrangler secret put [-e prod] <NAME>):

• CF_TOKEN: a token with edit permission on the zone's DNS (go to your profile and create a token with the DNS:Edit permission on your CF Zone)
• CF_ZONE: the CF zone id, as listed on the dashboard of the zone (scroll down, it's in the sidebar)
• DOMAIN: the record in the zone to set
• PASSWORD: the key to use to make sure people don't just update your DNS...

wrangler publish -e prod

Setup notes

I recommend setting the DOMAIN secret to a random sub domain and then pointing a CloudFlare proxied CNAME to it. That way, it is harder to find out what your home IP is.

Routes

• /dyndns: the URL you should point your script to. Accepts the following get parameters:
  • ipv4: the new IPv4
  • ipv6: the new IPv6
  • password: the password you chose in the step above
• /current-ip: returns the IP of the caller (use curl -4 or curl -6 to make sure you get the right IP)
  • Note that the IPv6 returned here is not necessarily the IP of your router since NATing is not always used with IPv6