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Catalyst2950 and Catalyst2955 Switch Software Configuration Guide
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Chapter29 Configuring Network Securi ty with ACLs Displaying ACL Information
This example shows how to apply access list 2 on an interface to filter packets entering the interface:
Switch(config)# interface gigabitethernet0/2
Router(config-if)# ip access-group 2 in
Note The ip access-group interface configuration command is only valid when applied to a management
interface or a Layer 2 physical interface. ACLs cannot be applied to interface port-channels.
For inbound ACLs, after receiving a packet, the switch checks the packet against the ACL. If the ACL
permits the packet, the switch continues to process the packet. If the ACL rejects the packet, the switch
discards the packet.
When you apply an undefined ACL to an interface, the switch acts as if the ACL has not be en applied to
the interface and permits all packets. Remember this behavior if you use undefined ACLs for network
security.
Displaying ACL Information
You can display the ACLs that are configured on the switch, and you can display the ACLs tha t have
been applied to physical and management interfaces. This secti on consi sts of t h ese t opi cs:
•Displaying ACLs, page 29-21
•Displaying Access Groups, page 29-22

Displaying ACLs

You can display existing ACLs by using show commands.
Beginning in privileged EXEC mode, follow these steps to display access lists:
Step4 end Return to privileged EXEC mode.
Step5 show running-config Display the access list configuration.
Step6 copy running-config startup-config (Optional) Save your entries in the configuration file.
Command Purpose
Command Purpose
Step1 show access-lists [number | name] Show information about all IP and MAC address access lists or about a
specific access list (numbered or named).
Step2 show ip access-list [number | name] Show information about all IP address access lists or about a specific IP
ACL (numbered or named).