How Access Control Lists (ACLs) are processed in DAL

Introduction

This article describes how Access Control Lists (ACLs) are processed in DAL

Issue/Question

How does the DAL operating system evaluate Access Control Lists?

Solution

Access control Lists (ACLs) are evaluated from the top down. When evaluating traffic, the system checks it sequentially against:

1. IPv4

2. IPv6

3. Interfaces

4. Zones

If traffic is matched to anything configured in the ACL, it will be permitted. There is an implicit deny at the end of the ACL when anything is configured in it.

If the ACL is empty, there will be no implicit deny and all traffic is permitted for that service in DAL.