I thought I'd mention this, having run into it this morning when setting up a new system & this is a much easier & safer approach (I think) than that described in other forum threads like
https://forum.opnsense.org/index.php?topic=36994.0
as it doesn't require you store any credentials, and you can revoke the update token at any time on the FreeDNS control panel.
On the freedns.afraid.org interface:
- Navigate to the new update interface https://freedns.afraid.org/dynamic/v2/
- Make sure "Randomized update token" is the selected option.
- Copy the URL listed there: it'll be something like http://sync.afraid.org/u/blahblahlongcharacterstring
Then, in the dynamic DNS panel on opnsense:
- Make sure backend is 'native'
- Create a new item and set the following
- Service: custom
- Protocol: Custom GET
- Server: Paste in the URL you copied from the freedns.afraid.org panel above
- Hostname: this is required by the form, though I don't believe it's used, I set it to the domain I'm trying to update.
- Make sure to set "Interface to monitor" correctly
- Save and then apply settings.
Give it a minute or two to update, and you should notice the additional values in the Services: Dynamic DNS Settings page appear.