Examples: Acls In A Small Networked Office; Example: Numbered Acls; Examples: Extended Acls - Cisco Catalyst 2960-XR Security Configuration Manual

Configuring IPv4 ACLs

Examples: ACLs in a Small Networked Office

This example uses a standard ACL to filter traffic coming into Server B from a port, permitting traffic only
from Accounting's source addresses 172.20.128.64 to 172.20.128.95. The ACL is applied to traffic coming
out of routed Port 1 from the specified source address.
Switch(config)# access-list 6 permit 172.20.128.64 0.0.0.31
Switch(config)# end
Switch# how access-lists
Standard IP access list 6
10 permit 172.20.128.64, wildcard bits 0.0.0.31
Switch(config)# interface gigabitethernet1/0/1
Switch(config-if)# ip access-group 6 out
This example uses an extended ACL to filter traffic coming from Server B into a port, permitting traffic from
any source address (in this case Server B) to only the Accounting destination addresses 172.20.128.64 to
172.20.128.95. The ACL is applied to traffic going into routed Port 1, permitting it to go only to the specified
destination addresses. Note that with extended ACLs, you must enter the protocol (IP) before the source and
destination information.
Switch(config)# access-list 106 permit ip any 172.20.128.64 0.0.0.31
Switch(config)# end
Switch# show access-lists
Extended IP access list 106
10 permit ip any 172.20.128.64 0.0.0.31
Switch(config)# interface gigabitethernet1/0/1
Switch(config-if)# ip access-group 106 in

Example: Numbered ACLs

In this example, network 36.0.0.0 is a Class A network whose second octet specifies a subnet; that is, its
subnet mask is 255.255.0.0. The third and fourth octets of a network 36.0.0.0 address specify a particular host.
Using access list 2, the switch accepts one address on subnet 48 and reject all others on that subnet. The last
line of the list shows that the switch accepts addresses on all other network 36.0.0.0 subnets. The ACL is
applied to packets entering a port.
Switch(config)# access-list 2 permit 36.48.0.3
Switch(config)# access-list 2 deny 36.48.0.0 0.0.255.255
Switch(config)# access-list 2 permit 36.0.0.0 0.255.255.255
Switch(config)# interface gigabitethernet2/0/1
Switch(config-if)# ip access-group 2 in

Examples: Extended ACLs

In this example, the first line permits any incoming TCP connections with destination ports greater than 1023.
The second line permits incoming TCP connections to the Simple Mail Transfer Protocol (SMTP) port of
host 128.88.1.2. The third line permits incoming ICMP messages for error feedback.
Switch(config)# access-list 102 permit tcp any 128.88.0.0 0.0.255.255 gt 1023
Switch(config)# access-list 102 permit tcp any host 128.88.1.2 eq 25
Switch(config)# access-list 102 permit icmp any any
Switch(config)# interface gigabitethernet2/0/1
Switch(config-if)# ip access-group 102 in
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Catalyst 2960-XR Switch Security Configuration Guide, Cisco IOS Release 15.0(2)EX1
IPv4 ACL Configuration Examples
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