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Turning my ESP32 into a DNS sinkhole to fight doomscrolling

(amanvir.com)
105 points venusgirdle | 5 comments | 28 Feb 25 10:39 UTC | HN request time: 0.208s | source
1. adamrmcd ◴[02 Mar 25 20:59 UTC] No.43235014[source]▶
Neat idea, but my takeaway is I had no idea that DNS also runs on UDP/53.. I always thought it was TCP only! #TIL

The author cites it as performance reasons, but at this scale, even the uplink to cloudflare, would be negligible, no?

replies(4): >>43235271 #>>43235315 #>>43235633 #>>43239993 #
2. loloquwowndueo ◴[02 Mar 25 21:22 UTC] No.43235271[source]▶
That’s odd because DNS is the quintessential UDP-based protocol. “From the time of its origin in 1983 the DNS has used the User Datagram Protocol (UDP) for transport over IP.”. DNS over TCP was only introduced as a later addition (admittedly, in 1989).
3. teruakohatu ◴[02 Mar 25 21:26 UTC] No.43235315[source]▶
With 'normal' DNS, UDP with the default and TCP is used if the packet size becomes too large. There are other TCP-only variants such as DoT (DNS over TLS) and DoH (DNS over HTTPS).

I don't think the performance would matter much with some basic caching (or even just OS-level caching), but there is limited memory in an ESP so maybe that is it. I have never noticed issues with DoT and DoH which are theoretically much heavier protocols.

4. huang_chung ◴[02 Mar 25 21:58 UTC] No.43235633[source]▶
> I always thought it was TCP only!

So did the NIH firewall administrator:

https://news.ycombinator.com/item?id=43229201

5. stavros ◴[03 Mar 25 09:32 UTC] No.43239993[source]▶
Huh, I didn't know it had a TCP option, I thought it was UDP-only.