Port Acls - Cisco WS-C3750-48PS-S Software Configuration Manual

Chapter 31 Configuring Network Security with ACLs
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Port ACLs

Port ACLs are ACLs that are applied to Layer 2 interfaces on a switch. Port ACLs are supported only on
physical interfaces and not on EtherChannel interfaces and can be applied only on interfaces in the
inbound direction. These access lists are supported on Layer 2 interfaces:
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The switch examines ACLs associated with all inbound features configured on a given interface and
permits or denies packet forwarding based on how the packet matches the entries in the ACL. In this way,
ACLs are used to control access to a network or to part of a network.
port ACLs to control access to a network when all workstations are in the same VLAN. ACLs applied at
the Layer 2 input would allow Host A to access the Human Resources network, but prevent Host B from
accessing the same network. Port ACLs can only be applied to Layer 2 interfaces in the inbound
direction.
Figure 31-1 Using ACLs to Control Traffic to a Network
78-16180-02
When a VLAN map, input router ACL, and input port ACL exist in an SVI, incoming packets
received on the ports to which a port ACL is applied are only filtered by the port ACL. Incoming
routed IP packets received on other ports are filtered by both the VLAN map and the router ACL.
Other packets are filtered only by the VLAN map.
When a VLAN map, output router ACL, and input port ACL exist in an SVI, incoming packets
received on the ports to which a port ACL is applied are only filtered by the port ACL. Outgoing
routed IP packets are filtered by both the VLAN map and the router ACL. Other packets are filtered
only by the VLAN map.
Standard IP access lists using source addresses
Extended IP access lists using source and destination addresses and optional protocol type
information
MAC extended access lists using source and destination MAC addresses and optional protocol type
information
Human
Resources
network
= ACL denying traffic from Host B
and permitting traffic from Host A
= Packet
Host A
Host B
Research &
Development
network
Catalyst 3750 Switch Software Configuration Guide
Understanding ACLs
Figure 31-1 is an example of using
31-3