Cisco Gigabit Ethernet Switch Module for HP p-Class BladeSystem Software Configuration Guide

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Cisco Gigabit Ethernet Switch Module for HP p-Class BladeSystem Software Configuration Guide
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Chapter 26 Configuring Network Security with ACLs
Configuring IPv4 ACLs
To remove an ACL from a terminal line, use the no access-class access-list-number {in | out} line
configuration command.
Applying an IPv4 ACL to an Interface
This section describes how to apply IPv4 ACLs to network interfaces. Note these guidelines:
• Apply an ACL only to inbound Layer 2 interfaces.
• When controlling access to an interface, you can use a named or numbered ACL.
• If you apply an ACL to a Layer 2 interface that is a member of a VLAN, the Layer 2 (port) ACL
takes precedence over a VLAN map applied to the VLAN. Incoming packets received on the Layer
2 port are always filtered by the port ACL.
Beginning in privileged EXEC mode, follow these steps to control access to an interface:
To remove the specified access group, use the no ip access-group {access-list-number | name} {in}
interface configuration command.
This example shows how to apply access list 2 to a port to filter packets entering the port:
Switch(config)# interface gigabitethernet0/1
Router(config-if)# ip access-group 2 in
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 been applied
to the interface and permits all packets. Remember this behavior if you use undefined ACLs for network
security.
Step 4
end Return to privileged EXEC mode.
Step 5
show running-config Display the access list configuration.
Step 6
copy running-config startup-config (Optional) Save your entries in the configuration file.
Command Purpose
Command Purpose
Step 1
configure terminal Enter global configuration mode.
Step 2
interface interface-id Identify a specific interface for configuration, and enter interface
configuration mode.
Step 3
ip access-group {access-list-number |
name} {in}
Control access to the specified interface.
Step 4
end Return to privileged EXEC mode.
Step 5
show running-config Display the access list configuration.
Step 6
copy running-config startup-config (Optional) Save your entries in the configuration file.