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Catalyst 3750-X and 3560-X Switch Software Configuration Guide
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Chapter 37 Configuring Network Security with ACLs
Configuring IPv4 ACLs
ACLs in a Small Networked Office
Figure 37-3 shows a small networked office environment with routed Port 2 connected to Server A,
containing benefits and other information that all employees can access, and routed Port 1 connected to
Server B, containing confidential payroll data. All users can access Server A, but Server B has restricted
access.
Use router ACLs to do this in one of two ways:
• Create a standard ACL, and filter traffic coming to the server from Port 1.
• Create an extended ACL, and filter traffic coming from the server into Port 1.
Figure 37-3 Using Router ACLs to Control Traffic
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# show 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
Server A
Benefits Server B
Payroll
Port 2 Port 1
Accounting
172.20.128.64-95
Human Resources
172.20.128.0-31
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