Dell PowerSwitch S4820T Configuration Guide for the S4820T System 9.112.0P1 - Page 116

To filter traffic on Telnet sessions, use only standard ACLs in the access-class command. Counting ACL Hits You can view the number of packets matching the ACL by using the count option when creating ACL entries. 1 Create an ACL that uses rules with the count option. Refer to Configure a Standard IP ACL Filter. 2 Apply the ACL as an inbound or outbound ACL on an interface. 3 show ip accounting access-list EXEC Privilege mode View the number of packets matching the ACL. Configure Ingress ACLs Ingress ACLs are applied to interfaces and to traffic entering the system. These system-wide ACLs eliminate the need to apply ACLs onto each interface and achieves the same results. By localizing target traffic, it is a simpler implementation. To create an ingress ACL, use the ip access-group command in EXEC Privilege mode. The example shows applying the ACL, rules to the newly created access group, and viewing the access list. Example of Applying ACL Rules to Ingress Traffic and Viewing ACL Configuration To specify ingress, use the in 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 tengigabitethernet 1/1 Dell(conf-if-te1/1)#ip access-group abcd in Dell(conf-if-te1/1)#show config ! tengigabitethernet 1/1 no ip address ip access-group abcd in no shutdown Dell(conf-if-te1/1)#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 tengigabitethernet 1/1 seq 5 permit tcp any any seq 10 deny icmp any any seq 15 permit 1.1.1.2 Configure Egress ACLs Egress ACLs are applied to line cards and affect the traffic leaving the system. Configuring egress ACLs onto physical interfaces protects the system infrastructure from attack - malicious and incidental - by explicitly allowing only authorized traffic. These system-wide ACLs eliminate the need to apply ACLs onto each interface and achieves the same results. By localizing target traffic, it is a simpler implementation. To restrict egress traffic, use an egress ACL. For example, when a denial of service (DOS) attack traffic is isolated to a specific interface, you can apply an egress ACL to block the flow from the exiting the box, thus protecting downstream devices. 116 Access Control Lists (ACLs)