Eddie on RPi4B that runs Pi-Hole

[Tubular 1]

My Raspberry Pi runs Pi-Hole for all my home network device connections.
I always connect any device I use to AirVPN, when I'm using them (usually one at a time in use).
I use AirVPN's DNS filter list to block trackers (in addition to using browser extensions to block those).
Today for the first time I installed Eddie on my RPi, because I've started using the Pi to stream internet radio/TV, and because I realized my IPTV client probably wasn't blocking trackers.
To my pleasant surprise, I can connect to AirVPN on the RPi, while still connecting to AirVPN on other devices in my network that are being routed through Pi-Hole (which is installed on the RPi, which is now also connected to AirVPN). I was expecting that this would be treated as a double VPN connection, and would not work.
Can someone explain the mechanics for me? This is not really routing an AirVPN connection through a second AirVPN connection, is it?
Thanks!
P.S. I'm obviously not an expert here. 😉

EDIt: And I do realize the RPi isn't routing through Pi-Hole.

Edited ... by Tubular

[OpenSourcerer 1435]

2 hours ago, Tubular said:

Can someone explain the mechanics for me? This is not really routing an AirVPN connection through a second AirVPN connection, is it?

As long as you don't use the same key pair (device) on the same server with the same method, protocol and port, multiple connections are possible with any desktop/server OS.

And no, the only thing Pi-Hole is doing in your network is be a DHCP and DNS server. It's not a router.

[Tubular 1]

Is this an accurate description of what's happening in the above situation?

1.
Device (laptop) first gets DNS from Pi-hole (on RPi), but then I connect the laptop to AirVPN server and switch to AirVPN DNS. Now AirVPN connection is transiting through Pi-hole (with unreadable traffic), which is installed on the RPi, which is also connected to an AirVPN server. Result: AirVPN server 1 is chained through AirVPN server 2?

Or is it this, rather:

2.
Device (laptop) with AirVPN connection goes directly to router, is visible (but unreadable) in Pi-hole (on RPi).
RPi, which is also connected to an AirVPN server, also connects directly to router (obviously). Result: laptop and RPi are both connected to an AirVPN server, but one is not routing through the other. (Simply connecting any two of my devices to any two different AirVPN servers at the same time, but not chained.)

Thanks for your insights. I'm sure I just don't understand Pi-hole well enough. I was thinking that because it resides on the RPi, all traffic transiting to my router through Pi-hole is also routing through the RPi's network connection.
 

Edited ... by Tubular

[OpenSourcerer 1435]

1 minute ago, Tubular said:

Device (laptop) first gets DNS from Pi-hole (on RPi), but then I connect the laptop to AirVPN server and switch to AirVPN DNS. Now AirVPN connection is transiting through Pi-hole (with unreadable traffic), which is installed on the RPi, which is also connected to an AirVPN server. Result: AirVPN server 1 is chained through AirVPN server 2?

It's a bit ambiguous if you describe it like that.

• Your computer gets the DNS server setting from a DHCP server when it connects to the network (via copper cable, wireless, etc.), in this case Pi-Hole itself. Everytime your computer now wants to know the IP address of a name like airvpn.org, it asks Pi-Hole.
• Since Pi-Hole is connected to an AirVPN server (and assuming all traffic is routed through it), then all DNS queries from your computer are routed through the VPN. Computer -> Pi-Hole -> AirVPN server -> upstream DNS (whatever you configured in Pi-Hole).
• When you connect to AirVPN and Eddie for example overrides your configured DNS server to AirDNS, then AirDNS is what's used over the VPN tunnel established between your computer and the AirVPN server. Pi-Hole doesn't partake in any of this anymore. The way is: Computer -> AirVPN server.

There's never a chain. Even if you connect to AirVPN with your computer without setting AirDNS on it, the traffic will go through the tunnel on the computer while the DNS queries will go through Pi-Hole, which in turn routes the queries through its own AirVPN connection.

So all in all, it's #2.
 

12 minutes ago, Tubular said:

all traffic transiting to my router through Pi-hole is also routing through the RPi's network connection

You must understand that Pi-Hole doesn't route anything. It's first and foremost a DNS server forwarding queries to its configured upstream DNS servers, and a DHCP server which first and foremost assigns IP addresses to devices in its network. It's neither a firewall, nor a proxy, nor a router.

[Tubular 1]

OK, now it's starting to make more sense. Thanks for the reply and explanation!