Blocking DNS-over-https

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L3 Networker

Blocking DNS-over-https

Hi,

 

I plan to create security policy rules to block dns-over-https and dns-over-tls.   Is it also recommended to block dnscrypt?  

 

In regards to dns-over-https.  If the browser attempts this and fails, does it fallback to using the client's configured dns servers?


Accepted Solutions
L7 Applicator

the browser should fall back to regular dns if one of the encrypted versions is unavailable.

 

why are you blocking these?

Tom Piens - PANgurus.com
Like my answer? check out my book! amazon.com/dp/1789956374

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L7 Applicator

the browser should fall back to regular dns if one of the encrypted versions is unavailable.

 

why are you blocking these?

Tom Piens - PANgurus.com
Like my answer? check out my book! amazon.com/dp/1789956374

View solution in original post

L3 Networker

@reaper 

 

Reason for blocking is corporate policy is to allow dns requests from internal DNS servers only.  Also, they both create security risks that could allow tunneling of malicious traffic and also could potentially bypass your security policies

 

Palo Alto also recommends blocking.  

 

You don't believe they should be blocked?  I'd like to hear your reasons

L7 Applicator

@ce1028  i do believe in blocking them, but under the right circumstances

 

my first preference is to block all outbound DNS except the outbound connections from my inhouse DNS server for which i would force tls/https as much as possible (for privacy reasons)

 

in a second scenario, if there is no internal DNS i would encourage dns-over-tls/https as this provides more privacy

 

from the firewall you can ssl decrypt to still look inside and make sure there are not threats, but an outside listener should not be able to pick up on my dns traffic

Tom Piens - PANgurus.com
Like my answer? check out my book! amazon.com/dp/1789956374
L3 Networker

@reaper 

 

I agree your assessment. I'm all for encrypted dns, but I want all my dns requests coming from my internal dns servers, as you stated.

 

However, I thought dns-over-https uses certificate pinning, which would not allow it to be decrypted?

 

 

 

L7 Applicator

@ce1028  I thought pinning was by choice

Tom Piens - PANgurus.com
Like my answer? check out my book! amazon.com/dp/1789956374
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