Perhaps this is a weird question I have, but I’ve been watching some technotim videos lately and he seems to have local dns addresses for local services. Perhaps I’ve got this wrong, but if not: how would you go over doing this?
I have a pterodactyl dashboard, which I access locally using the machines IP and the port, but it would be great to have a pterodactyl.example.com domain, which isn’t accessible from other networks, but does work on my own network. I also still want some services exposed to the internet, so I’m not sure if this would work.
Or just point secret.local.mydomain.com to the LAN IP of the server.
That’s the gotcha that can bite you: if you’re sharing internal and external sites via a split horizon nginx config, and it’s accessible over the public internet, then the actual IP defined in DNS doesn’t actually matter.
If the attacker can determine that secret.local.mydomain.com is a valid server name, they can request it from nginx even if it’s got internal-only dns by including the header of that domain in their request, as an example, in curl like thus:
curl --header 'Host: secret.local.mydomain.com' https://your.public.ip.here -kAdmittedly this requires some recon which means 99.999% of attackers are never even going to get remotely close to doing this, but it’s an edge case that’s easy to work against by ACLs, and you probably should when doing split horizon configurations.
But the attacker should know the internal and the external DNS. If the internal DNS doesn’t have any SSL certificate on its name, it’s impossible to discover.
By the way, I always suggest to reach services through VPN and use something like Cloudflare tunnel for services that must be public.
P.s. Shouldn’t public and private DNS be inverted in your curl example?