Connectivity Guide

• Apply the ACL as an inbound or outbound ACL on an interface in CONFIGURATION mode, and view the number of packets matching
the ACL.
show ip access-list {in | out}
Ingress ACL lters
To create an ingress ACL lter, use the ip access-group command in EXEC mode. To congure ingress, use the in keyword. Apply
rules to the ACL with the ip access-list acl-name command. To view the access-list, use the show access-lists command.
1 Apply an ingress access-list on the interface in INTERFACE mode.
ip access-group access-group-name in
2 Return to CONFIGURATION mode.
exit
3 Create the access-list in CONFIGURATION mode.
ip access-list access-list-name
4 Create the rules for the access-list in ACCESS-LIST mode.
permit ip host ip-address host ip-address count
Apply ACL rules to access-group and view access-list
OS10(config)# interface ethernet 1/1/28
OS10(conf-if-eth1/1/28)# ip access-group abcd in
OS10(conf-if-eth1/1/28)# exit
OS10(config)# ip access-list acl1
OS10(conf-ipv4-acl)# permit ip host 10.1.1.1 host 100.1.1.1 count
Egress ACL lters
Egress ACL lters aect the trac leaving the network. Conguring egress ACL lters onto physical interfaces protects the system
infrastructure from a malicious and intentional attack by explicitly allowing only authorized trac. These system-wide ACL lters eliminate
the need to apply ACL lters onto each interface.
You can use an egress ACL lter to restrict egress trac. For example, when you isolate denial of service (DoS) attack trac to a specic
interface, and apply an egress ACL lter to block the DoS ow from exiting the network, you protect downstream devices.
1 Apply an egress access-list on the interface in INTERFACE mode.
ip access-group access-group-name out
2 Return to CONFIGURATION mode.
exit
3 Create the access-list in CONFIGURATION mode.
ip access-list access-list-name
4 Create the rules for the access-list in ACCESS-LIST mode.
seq 10 deny ip any any count fragment
Apply rules to ACL lter
OS10(config)# interface ethernet 1/1/29
OS10(conf-if-eth1/1/29)# ip access-group egress out
OS10(conf-if-eth1/1/29)# exit
OS10(config)# ip access-list egress
OS10(conf-ipv4-acl)# seq 10 deny ip any any count fragment
View IP ACL lter conguration
OS10# show ip access-lists out
Egress IP access-list abcd
Active on interfaces :
Access Control Lists
887