As we've said before and now, the beauty of technology in general and computer networks in particular is that everything is self-explanatory. From there, an Access Control List (ACL) is a configuration in the router consisting of several commands that control whether a router forwards or drops packets based on information found in the packet header. Thus, ACLs enable the following tasks:
- Limiting network traffic to increase network performance
- Providing traffic flow control
- Providing a basic level of security for network access
- Filtering traffic based on traffic type
- Screening hosts to permit or deny access to network services
In this section, other than discussing ACL concepts, the possible scenarios of problems that may occur with ACLs are covered too.