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Cisco IE 2000 Switch Software Configuration Guide
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Chapter 37 Configuring Network Security with ACLs
Configuration Examples for Network Security with ACLs
Router ACLs function as follows:
• The hardware controls permit and deny actions of standard and extended ACLs (input and output)
for security access control.
• If log has not been specified, the flows that match a deny statement in a security ACL are dropped
by the hardware if ip unreachables is disabled. The flows matching a permit statement are switched
in hardware.
• Adding the log keyword to an ACE in a router ACL causes a copy of the packet to be sent to the
CPU for logging only. If the ACE is a permit statement, the packet is still switched and routed
in hardware.
Routed ACLs: Examples
Figure 37-2 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 37-2 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
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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