EDIT: Thanks for the info guys! Very excited to get this all set up
At the moment I have a bunch of self-hosting services hosted in the cloud. I plan to get rid of my cloud resources entirely and run stuff on some server hardware I acquired recently but my ISP doesn’t give me a static IP and I’m behind a NAT or whatever it’s called (the thing that makes multiple people’s home connections be behind a single public IP) so I don’t think I can even expose directly to the internet. So my plan is to have a very small and cheap server at a data center and proxy my actual server behind that.
My question is, is there a way that I can set things up so that the same domain can connect directly to the server when I’m at home, and to the proxy when I’m not? The difference would be what connection I’m connected to (my home WiFi vs 5G/others’ WiFi). I’m thinking I could maybe run DNS on the server and configure my router to use that as a DNS server, but wouldn’t my phone/laptop cache DNS entries? So it’d still try to connect to the local IP even when I’m out.
Use a dedicated DNS-service on your local network which has the local IPs in it’s DB. Use that DNS-service as your first/primary DNS on your local network (settings).
This is the perfect opportunity to set up a pihole. Its primary purpose is to block ads network wide but since it is essentially a DNS with a block list you can also set custom dns-entries.
Way ahead of you, was looking at dnsmasq earlier then pi-hole, then turns out pi-hole has dnsmasq rolled into it now so I don’t even have to configure separate services!
Yes, this is called split horizon dns, basically, you have to control the DNS servers.
First, make a forwarding/resolver/cache, tell it to forward all requests for your_domain to your internal authoritative DNS server, it will return your internal IPs, externally though, when that domain is looked up, it will return the public ips of that host.
Not exactly the solution you’re describing but Tailscale or ZeroTier could be the solution to your problem.
They’re P2P VPNs which don’t require static IPs or even open ports.
I set up Tailscale to forward my home subnet via my NAS. That allows transparent access of the NAS itself and any other device on the home network no matter where I am (as long as there’s internet).
Depending on your wifi/router you could add a static DNS record for your domain while on the hi home network. The cached DNS will only matter while connected to the home wifi network. While on 5g you’ll pick up the public DNS record. If it does some how cache the local DNS while public then shorten the ttl in the local DNS record
There’s some great advice here on how to accomplish this, but a note of caution: If you’re doing this split DNS on a device that you expect to be able to walk out the door with and continue working properly… Some apps will cache DNS lookups even beyond the configured TTL. Meaning that a running app that thinks your server has a particular IP might stop working as soon as you walk outside of WiFi range and that IP is no longer reachable. And it might stay not working for quite a while. Ask me how I know this. :D
I feel like I know the answer already but how do you know this?
Because I tried this exact scenario with the Home Assistant app. Local IP for my HA server’s hostname configured on my home router, public IP for the hostname elsewhere. I walk out my front door with the HA android app running on my phone, boom, loses connectivity to the HA server as soon as I’m out of wifi range and never recovers… The local IP is no longer reachable and the app isn’t smart enough to look up the new one.
