Create or update a security policy rule and reference an
anti-spyware profile and a custom URL category list (ObjectsCustom ObjectsURL Category) containing the approved list of DoH servers.
Create a block policy to decrypt HTTPS traffic and
block all remaining unsanctioned DoH traffic that is not explicitly
allowed by the custom URL category list (referenced in step 5) by
using the App-ID: dns-over-https and
the following URL category: encrypted-dns.
If you already have an existing block policy to block
DoH traffic, verify that the rule is placed below the previous security
policy rule used to match with specific DoH resolvers listed in
a custom URL category list object.
(Optional) Search for activity on the firewall for HTTPS-encrypted
DNS queries that have been processed using DNS Security.
Select MonitorLogsTraffic and
filter based on the application using dns-over-https,
for example, ( app eq dns-over-https ).
Select a log entry to view the details of a detected
DNS threat.
The Application should display
dns-over-https in the General pane of the
detailed log view, indicating that this is DoH traffic that has
been processed using DNS Security. Other relevant details about
the threat are displayed in their corresponding windows.