Pi-hole has helped improve my “relationship” with Firefox, or better phrased with Firefox forks like LibreWolf and Tor browser. Cool thing with Pi-hole is that you can watch the query log and see what happened in the background while you were surfing the Internet. I learned that :
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After removing the sponsored shortcuts in Firefox and putting your own shortcuts there Firefox will make connections each time you start the browser. So, if you would have icons on your quick start page in Firefox for let’s say EFF, Lemmy, Mastodon, HackerNews, with each Firefox start up, it would query these sites. which I didn’t like so much. Since then I’ve gone back to a complete blank start page, removing search and all those quick start icons, using just toolbar folders with bookmarks.
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Pi-hole defaults to blocking telemetry for Firefox and Thunderbird.
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Signal uses Google servers I saw via Pi-hole. I thought that they were using Amazon servers, but looking at Wikipedia for the history of Signal hosting I learned that Signal went back to Google for hosting.
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Firefox push notification services are hosted on Google servers. LibreWolf removes a lot of Google things that Firefox has by default, but not the push parts. With Pi-hole it is very easy to block that.
Right, so flowing that link there are three ways for DNS:
Classic on port 53,
Dns over TLS on port 853
Dns over https.
The first two can be blocked, because they have specific ports exclusively assigned to them. DoH can’t be blocked reliably, because it is encrypted and on a common port. Though blocking 443 on common DNS resolvers can force some clients to fall back to one of the variants that can be blocked/redirected