Recover from OPNsense GUI lockout

Somehow a gateway change locked me out of my OPNsense GUI. I still have the Anti-Lockout Rule enabled in the firewall so this shouldn't have been possible, but alas...

While I didn't have GUI access, I could still SSH. It turns out, OPNsense's main configuration file is /conf/config.xml.

So, first I backed up the configuration cp /conf/config.xml /conf/config.xml.bak.

Then I opened it in vi to find my recent changes (I had enabled a route and intervace named OpenVPN) vi /conf/config.xml.

After reversing my edits I saved the file :wq and ran reboot - I was back in!