Even Palo Alto notes that they can only effectively block DoH if you’re MITMing all https traffic already (e.g. using a root certificate on corporate-managed devices). If not able to MITM the connection, it will still try to block popular DoH providers, though.
It’s trivial for me to detect and block dns over https with modern firewalls.
How? I don’t see what could find dns-over-https in the middle of other https traffic?
there is a lot more to modern firewall app detection than ports. My Palo Alto has a specific category to detect and block dns over https.
Even Palo Alto notes that they can only effectively block DoH if you’re MITMing all https traffic already (e.g. using a root certificate on corporate-managed devices). If not able to MITM the connection, it will still try to block popular DoH providers, though.
https://live.paloaltonetworks.com/t5/blogs/protecting-organizations-in-a-world-of-doh-and-dot/ba-p/313171