Blocking DNS-over-https

cancel
Showing results for 
Search instead for 
Did you mean: 

Blocking DNS-over-https

L4 Transporter

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?

1 ACCEPTED SOLUTION

Accepted Solutions

Cyber Elite
Cyber Elite

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

 

why are you blocking these?

Tom Piens
PANgurus - (co)managed services and consultancy

View solution in original post

6 REPLIES 6

Cyber Elite
Cyber Elite

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

 

why are you blocking these?

Tom Piens
PANgurus - (co)managed services and consultancy

@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

@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 - (co)managed services and consultancy

@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?

 

 

 

Cyber Elite
Cyber Elite

@ce1028  I thought pinning was by choice

Tom Piens
PANgurus - (co)managed services and consultancy

Hello,

I have tow cases, one we can decrypt the traffic and this is which is possible to allow secured DNS.

my second case in another network with no decryption applied "network requirements", here should I should I block the DNS_Over_https, and allow only benign DNS traffic to inhouse DNS server?

Notice:

       even without decryption rule, how possible to the firewall to read into the ssl traffic and discover the DNS_over_https?

Thank you

MR
Like what you see?

Show your appreciation!

Click Like if a post is helpful to you or if you just want to show your support.

Click Accept as Solution to acknowledge that the answer to your question has been provided.

The button appears next to the replies on topics you’ve started. The member who gave the solution and all future visitors to this topic will appreciate it!

These simple actions take just seconds of your time, but go a long way in showing appreciation for community members and the LIVEcommunity as a whole!

The LIVEcommunity thanks you for your participation!