In your Tailscale DNS panel, disable “Use with exit node” option for your nameservers.

When turned on, that option actually allows you to talk directly to nameservers without tunneling DNS queries through the exit node. Since Quad9 in fact has a worldwide CDN, this would leak your (general) DNS query location.

I believe Tailscale send the queries in parallel and fetch the faster response, which is Quad9 in this case. Ideally for your use case, all your queries should be able to reach and show up in Pi-hole’s logs. Use tailscale dns commands for further debugging

Glad to know you got it working.

When you use a VPN as a matter of privacy, I believe you should use their DNS service too to blend in with the crowd. Because of DNS leaks, websites would likely know which DNS server you’re querying from, so using a selfhosted one instead of a VPN’s can be a major uniqueness vector. On the contrary however, I’ve seen many do exactly that, so I guess it’s not as big of an issue. So it’s your choice ultimately.

Now, if you opt for commercial VPN’s DNS servers, be aware that don’t usually block any ads (if they do it’s likely a paid option), and you’d want to configure your own local zones too. To intercept DNS queries and forward only the approved ones to the VPN, I think you have 2 options:

• Host Technitium on the VPN’d machine (your computer) and set up blocklists there. Create Conditional Forwarding zones: 1 towards the main TDNS server for your local domains, and the rest towards the 10.2.0.1 server for your public queries. Technitium may be overkill, AdGuard Home can also do this.
• Configure your main TDNS server to forward queries via the VPN tunnel. This requires the VPN tunnel having an available SOCKS5/HTTP proxy, to be used with TDNS’ Proxy and Forwarders options. Even better, you may use the Advanced Forwarding app to only use this routing for the VPN’d device, and use another routing for other devices

One solution is to resolve all my subdomains on /etc/hosts so it never has to leave the box, but I’m curious what a more experienced net admin would suggest.

Not a net admin but I would enforce a LAN-only DNS server for all relevant clients and put the records there. And/or put such an infra behind a VPN like Tailscale so bots don’t see it.

Yeah they registered a wildcard but queries contain the full domain

Have you solved your problem? It seems like there are some issues with your setup:

TDNS is set to “allow recursion only for private networks” this means that if something external tried to resolve using my TDNS they’ll be refused, correct?

Correct. It only accept recursion queries from private networks and can make outbound requests to the internet as normal

10.2.0.1 turned out to be my vpn’s dns server

On the computer, you’re also using your VPN’s DNS service accessible within the VPN tunnel (hence the weird IP address). If you wanna use Technitium you should disable such service

I set NAT rules to force TDNS port 53 routing. TDNS is set to forward to quad9 and cloud flare externally. DNS blocking lists are set in TDNS.

Unable to reach external net when NAT rules active.

If you’re forcing every device to talk to TDNS, then your TDNS server is also talking to itself and cannot make queries to Cloudflare/Quad9 on port 53. You can either:

• Create an exception rule to allow your TDNS address to talk to Cloudflare/Quad9, or
• Use DNS-over-HTTPS/DNS-over-TLS as your TDNS forwarder protocols as they aren’t affected by rules on port 53 (recommended for encryption)

It seems the DHCP is handing out the fire wall’s ip for DNS server, 100.100.100.1 is that the expected behavior since DNSmasq should be forwarding to TDNS 100.100.100.333.

Yes it’s expected, if you’re telling your clients to forward their queries to dnsmasq, and then let dnsmasq forward those queries to Technitium. If you want clients to talk directly to TDNS instead, set the DHCP option to advertise its address and don’t use your firewall’s address as a forwarder. I prefer the second option as it’ll give you correct client IPs in query logs and save some round trips.

I don’t really know what I’m doing with zones but I have a primary zone set with example.com. I set some static hosts records in this zone and enabled reverse lookup, expecting servicehost.example.com

If you can query the zone and its reverse PTR record in Technitium’s DNS client, then you’ve properly set it up. Remember you’ll have to tick the PTR options when setting up said record. Also you can open an issue on Technitium’s Github or their subreddit for assistance.

My guess would be NSEC zone walking if your DNS provider supports DNSSEC. But that shouldn’t work with unregistered or wildcard domains

The next guess would be during setup, someone somewhere got ahold of your SNI (and/or outgoing DNS requests). Maybe your ISP/VPN service actually logs them and announce it to the world

I suggest next time, try setting up without any over-the-internet traffic at all. E.g. always use curl with the --resolve flag on the same VM as Apache to check if it’s working

Non-federated Matrix server with rooms bridged to Discord/Whatsapp/Slack/whatever, so everyone can join.

Use standard webapps for other stuff like polls, surveys, events etc and send the URL to an announcement channel. Not sure of exact solutions but if one app can do it all and send email reminders for them, thatd be great. Same can be done for VoIP with Jitsi links, or even Z**m links.

Backup the databases if you need the chat logs. All of this should be doable with a small VPS, but a mini PCs cluster could be better