Setup Guide

Applying Egress ACLs
Egress ACLs are supported on interfaces and aect the trac leaving the system.
Conguring egress ACLs onto physical interfaces protects the system infrastructure from attack — malicious and incidental — by explicitly
allowing only authorized trac. These system-wide ACLs eliminate the need to apply ACLs onto each interface and achieves the same
results. By localizing target trac, it is a simpler implementation.
To restrict egress trac, use an egress ACL. For example, when a direct operating system (DOS) attack trac is isolated to a specic
interface, you can apply an egress ACL to block the ow from the exiting the box, thus protecting downstream devices.
To create an egress ACL, use the ip access-group command in EXEC Privilege mode. The example shows viewing the conguration,
applying rules to the newly created access group, and viewing the access list.
Example of Applying ACL Rules to Egress Trac and Viewing ACL Conguration
To specify ingress, use the out keyword. Begin applying rules to the ACL with the ip access-list extended abcd command. To
view the access-list, use the show command.
Dell(conf)#interface gige 0/0
Dell(conf-if-gige0/0)#ip access-group abcd out
Dell(conf-if-gige0/0)#show config
!
gigethernet 0/0
no ip address
ip access-group abcd out
no shutdown
Dell(conf-if-gige0/0)#end
Dell#configure terminal
Dell(conf)#
ip access-list extended abcd
Dell(config-ext-nacl)#permit tcp any any
Dell(config-ext-nacl)#deny icmp any any
Dell(config-ext-nacl)#permit 1.1.1.2
Dell(config-ext-nacl)#end
Dell#
show ip accounting access-list
!
Extended Ingress IP access list abcd on gigethernet 0/0
seq 5 permit tcp any any
seq 10 deny icmp any any
seq 15 permit 1.1.1.2
Applying Layer 3 Egress ACLs on Control-Plane Trac
By default, packets originated from the system are not ltered by egress ACLs.
For example, if you initiate a ping session from the system and apply an egress ACL to block this type of trac on the interface, the ACL
does not aect that ping trac. The Control Plane Egress Layer 3 ACL feature enhances IP reachability debugging by implementing
control-plane ACLs for CPU-generated and CPU-forwarded trac. Using permit rules with the count option, you can track on a per-ow
basis whether CPU-generated and CPU-forwarded packets were transmitted successfully.
1 Apply Egress ACLs to IPv4 system trac.
CONFIGURATION mode
ip control-plane [egress filter]
2 Apply Egress ACLs to IPv6 system trac.
CONFIGURATION mode
ipv6 control-plane [egress filter]
3 Create a Layer 3 ACL using permit rules with the count option to describe the desired CPU trac.
Access Control Lists (ACLs)
133