DynamicDNS help request

[seamus]

I've configured the DynamicDNS updater in OPNsense, but I want a "backup" solution.

Is there a way to have OPNsense send an email (or otherwise communicate) when the IP address on the WAN-side changes?

[Paul.C]

I'd suggest you try DNS-O-Matic, which is a dynamic DNS aggregator, and set it up with your current dynamic DNS service provider, plus DSLReports line monitoring service. Not quite what you asked for, but may suit your need.

Another possibility is to use an IP monitoring service, provided it could be configured to check for something more specific than 'responds to pings' (because if your current IP is reassigned to someone else, their gear may still respond to the pings). A quick google search will turn up plenty of services that will monitor an IP address, some of which are free for basic service.

At least for me, knowing that using my dynamic DNS name still reaches my gear is the most important thing. If not, I want to know. If everything is working correctly, I don't really need to know my IP address changed.

- Paul

[Paul.C]

Just did a quick search, and https://uptimerobot.com/ looks like it could be one option. The free tier allows you to do various types of tests (more than just ping) and will monitor up to fifty IPs, every five minutes, with email notifications for free. More frequent checks, with SMS and/or voice calls on upgraded plans ($4.50/mo and up).

- Paul

p.s. I don't use them myself, can't endorse (or otherwise) their services.

[seamus]

Thank you for the suggestion. I looked at them (briefly), but it didn't seem that they were capable of doing what I need: I need to know when my IP address has been changed by my ISP. It's important because I'm away from my "home network" for months at a time, and I use the VPN to connect... which requires I know the IP address. And yes, I know OPNsense has a dynamic DNS client that updates my hostname (I use freedns), but I won't know that works until the IP address changes as there isn't a way to test & confirm it's working.

Anyway - I've found what seems to be a viable approach for doing this! I've not yet cobbled it into a working solution, but I hope to do that soon. The approach is to use one of the "what's my IP address" sites (e.g. https://www.whatsmyip.org/) in a cron job, then sending out an SMS or email to myself. FWIW, and in case it's of any interest to anyone else, the light came on after seeing this post on StackExchange: https://unix.stackexchange.com/questions/22615/how-can-i-get-my-external-ip-address-in-a-shell-script.

I should have thought of this before posting my question... I guess I got locked in on the idea that I should be able to accomplish this inside the OPNsense framework.