Define Traffic to Decrypt
Table of Contents
Define Traffic to Decrypt
Use Decryption Policy rules to define the traffic you
decrypt and the traffic you choose not to decrypt because of regulations,
business reasons, or privacy reasons.
A Decryption policy rule allows you to define traffic
that you want the firewall to decrypt and to define traffic that
you choose to exclude from decryption
because the traffic is personal or because of local regulations,
for example.
Attach a Decryption profile to each Decryption policy rule to
enable certificate checks, session mode checks, failure checks,
and protocol and algorithm checks, depending on the profile. These
checks prevent risky connections, such as sessions with untrusted
certificate issuers, weak protocols, ciphers, and algorithms, and servers
that have certificate issues.
Review the Decryption deployment best
practices checklist to ensure that you understand the recommended
best practices.
As a best practice, you should always block known dangerous URL Filtering categories such
as malware, phishing, dynamic-dns, unknown, command-and-control,
proxy-avoidance-and-anonymizers, copyright-infringement, extremism,
newly-registered-domain, grayware, and parked. If you must allow
any of these categories for business reasons, you must decrypt them
and apply strict Security profiles to the traffic.
URL categories that you should always decrypt if you allow them
include: online-storage-and-backup, web-based-email, web-hosting, personal-sites-and-blogs,
and content-delivery-networks.
In Security policy, block Quick UDP Internet
Connections (QUIC) protocol unless for business reasons, you want
to allow encrypted browser traffic. Chrome and some other browsers
establish sessions using QUIC instead of TLS, but QUIC uses proprietary
encryption that the firewall can’t decrypt, so potentially dangerous
traffic may enter the network as encrypted traffic. Blocking QUIC
forces the browser to fall back to TLS and enables the firewall
to decrypt the traffic.
Create a Security policy rule to block
QUIC on its UDP service ports (80 and 443) and create a separate
rule to block the QUIC application. For the rule that blocks UDP
ports 80 and 443, create a Service () that includes UDP
ports 80 and 443:
Use the
Service to specify the UDP ports to block for QUIC. In the second
rule, block the QUIC application:
