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Example of Applying ACL Rules to Egress Traffic and Viewing ACL Configuration
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 tengige 0/0
Dell(conf-if-te-0/0)#ip access-group abcd out
Dell(conf-if-te-0/0)#show config
!
TengigEthernet 0/0
no ip address
ip access-group abcd out
no shutdown
Dell(conf-if-te-0/0)#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 tengigEthernet 0/0
seq 5 permit tcp any any
seq 10 deny icmp any any
seq 15 permit 1.1.1.2
Applying Egress Layer 3 ACLs (Control-Plane)
By default, egress ACLs do not filter packets originated from the system.
For example, if you initiate a ping session from the system and apply an egress ACL to block this type of traffic on the interface,
the ACL does not affect that ping traffic. The Control Plane Egress Layer 3 ACL feature enhances IP reachability debugging by
implementing control-plane ACLs for CPU-generated and CPU-forwarded traffic. Using permit rules with the count option, you
can track on a per-flow basis whether CPU-generated and CPU-forwarded packets were transmitted successfully.
1. Apply Egress ACLs to IPv4 system traffic.
CONFIGURATION mode
ip control-plane [egress filter]
2. Apply Egress ACLs to IPv6 system traffic.
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 traffic.
CONFIG-NACL mode
permit ip {source mask | any | host ip-address} {destination mask | any | host ip-
address} count
Dell Networking OS Behavior: Virtual router redundancy protocol (VRRP) hellos and internet group management protocol
(IGMP) packets are not affected when you enable egress ACL filtering for CPU traffic. Packets the CPU sends with the source
address as the VRRP virtual IP address have the interface MAC address instead of VRRP virtual MAC address.
Configure ACLs to Loopback
You can apply ACLs on a Loopback interface.
Configuring ACLs onto the CPU in a Loopback interface protects the system infrastructure from attack — malicious and
incidental — by explicate allowing only authorized traffic.
The ACLs on Loopback interfaces are applied only to the CPU on the stack–unit — this application eliminates the need to apply
specific ACLs onto all ingress interfaces and achieves the same results. By localizing target traffic, it is a simpler implementation.
The ACLs target and handle Layer 3 traffic destined to terminate on the system including routing protocols, remote access,
simple network management protocol (SNMP), internet control message protocol (ICMP), and so on, Effective filtering of Layer
3 traffic from Layer 3 routers reduces the risk of attack.
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Access Control Lists (ACLs)