I’ve got Nginx Proxy Manager set up and it’s working wonderfully. However, I have some services I want to be able to access via reverse proxy, so I have SSL and can use a hostname to direct me to a service, but I only want to be able to access them via VPN. My best idea to make this work is to configure access so that only connections from my local network can access certain proxy hosts. This gives all external traffic a 403 on connection attempt. Is this the best or only way to go about it? Short of additional services such as Authelia and Fail2Ban of course, but I wanted to know if I have the right idea.
It’s down to having two distinct instances of nginx proxy and control of your local DNS (I use pihole as my DNS provider for local machines, but other DNS servers are available).
So you have your public proxy, which for the sake of this example we’ll call publicproxy.local, and you have your internal proxy which we’ll call localproxy.local.
You also have a dns provider, e.g. pihole.local
Configure your router to provide pihole.local as the dns server for any client on your local network via DHCP. Then configure your firewall to forward port 443 to publicproxy.local
In your local DNS provider configure CNAME or A records for any service you want to be able to access locally that point to localproxy.local.
In your external name servers configure CNAME or A records for any service you want to be able to access locally that point to your public IP or DDNS address.
For example:
Cloudflare has a CNAME record for plex.example.com which resolves to your public IP. Requests from outside your network hit your router which port forwards the request to publicproxy.local, publicproxy.local is configured to forward plex.example.com to 192.168.0.6 (where your Plex server lives)
pihole has a CNAME record for plex.example.com which resolves to localproxy.local. localproxy.local is also configured to forward plex.example.com to 192.168.0.6.
That means whether you request from outside or inside the network you’ll end up hitting 192.168.0.6, success!
Now, pihole also has a CNAME record for sonarr.example.com which resolves to localproxy.local and the proxy is configured to forward sonarr.example.com to 192.168.0.8 (where sonarr is in this example).
There’s no cloudflare record for that subdomain and the public proxy doesn’t recognise it. So if you can’t hit your public IP with a request for sonarr.example.com at all, short of having a host file configured to force it. Even if you forced the domain resolution the public proxy doesn’t recognise the URL and gives a 404.
However, if you were to go to sonarr.example.com locally you’d see sonarr.