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5 Cards in this Set

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What is an ACL?
An ACL is a router configuration script that controls whether a router permits or denies packets to pass based on criteria found in the packet header. ACLs are among the most commonly used objects in Cisco IOS software.
How many ACLs are allowed on a router?
Remember the three Ps. You can configure one ACL per protocol, per direction, per interface:

One ACL per protocol-To control traffic flow on an interface, an ACL must be defined for each protocol enabled on the interface.

One ACL per direction-ACLs control traffic in one direction at a time on an interface. Two separate ACLs must be created to control inbound and outbound traffic.

One ACL per interface-ACLs control traffic for an interface, for example, Fast Ethernet 0/0.
Dynamic ACL's (Lock and Key)
Users that want to traverse the router are blocked until they use Telnet to connect to the router and are authenticated

Lock-and-key is available for IP traffic only.

Dynamic ACLs are dependent on Telnet connectivity, authentication (local or remote), and extended ACLs.
Reflexive ACS's
Allows outbound traffic and limits inbound traffic in response to sessions that originate inside the router
Time-based ACLs
Allows for access control based on the time of day and week