Filter
Top Products
31-21
Cisco ME 3400 Ethernet Access Switch Software Configuration Guide
OL-9639-06
Chapter 31 Configuring Network Security with ACLs
Configuring IPv4 ACLs
When you enter the show ip access-lists privileged EXEC command, the match count displayed does
not account for packets that are access controlled in hardware. Use the show access-lists hardware
counters privileged EXEC command to obtain some basic hardware ACL statistics for switched and
routed packets.
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.
IPv4 ACL Configuration Examples
This section provides examples of configuring and applying IPv4 ACLs. For detailed information about
compiling ACLs, see the Cisco IOS Security Configuration Guide, Release 12.2 and to the Configuring
IP Services” section in the “IP Addressing and Services” chapter of the Cisco IOS IP Configuration
Guide, Release 12.2.
Figure 31-3 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.