Old Multisite Domains Still Serving Default Forum After Disabling Multisite

[pfaffman (Jay Pfaffman)]

OMG. I don’t remember the last time that I disagreed with you on a matter of fact. As a rule, when I see your avatar in a topic that I’ve commented on, I know that I’m going to learn something!

@RGJ

The reason this is happening is simple. Multisite will select a forum based on hostname

That’s true. They claim, though, that they switched to a standard install. I don’t believe them.

@RGJ

A non-multisite install will happily accept whatever hostname you point to it.

For several years now (but I think since let’s encrypt was available), on a standard install if you access it via any other hostname it’ll do a redirect (you can easily check by using the IP number and I just did another by setting forum.bigmouth.bass in /etc/hosts to a standard install and it redirected as expected. If you access it via https, which most browsers do by default now, you’ll get a certificate error.

If all that was required to access your site via some other hostname was DNS then anyone could hijack your site by creating a DNS record pointing to your site.

I think this is the magic:

templates/web.ssl.template.yml

My guess is that the app.yml still has something like this:

@pfaffman

   # do not redirect all hosts back to the main domain name
    - replace:
        filename: "/etc/nginx/conf.d/discourse.conf"
        from: /if \(\$http_host[^\}]*\}/m
        to: ""
    - replace:
        filename: "/etc/nginx/conf.d/discourse.conf"
        from: /return 301.*$/
        to: "return 301 https://$host$request_uri;"