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Catalyst 3750-X and 3560-X Switch Software Configuration Guide
OL-25303-03
Chapter 1 Configuring Network Security with ACLs
Configuring IPv4 ACLs
The first packet that triggers the ACL causes a logging message right away, and subsequent packets are
collected over 5-minute intervals before they appear or logged. The logging message includes the access
list number, whether the packet was permitted or denied, the source IP address of the packet, and the
number of packets from that source permitted or denied in the prior 5-minute interval.
Smart Logging
When smart logging is enabled on the switch and an ACL configured with smart logging is attached to
a Layer 2 interface (port ACL), the contents of packets denied or permitted because of the ACL are also
sent to a specified NetFlow collector. For more information about smart logging, see the “Configuring
Smart Logging” section on page 1-14.
Creating a Numbered Standard ACL
Beginning in privileged EXEC mode, follow these steps to create a numbered standard ACL:
Command Purpose
Step 1
configure terminal Enter global configuration mode.
Step 2
access-list access-list-number {deny | permit}
source [source-wildcard] [log | smartlog]
Define a standard IPv4 access list by using a source address and
wildcard.
The access-list-number is a decimal number from 1 to 99 or 1300
to 1999.
Enter deny or permit to specify whether to deny or permit access
if conditions are matched.
The source is the source address of the network or host from which
the packet is being sent specified as:
• The 32-bit quantity in dotted-decimal format.
• The keyword any as an abbreviation for source and
source-wildcard of 0.0.0.0 255.255.255.255. You do not need
to enter a source-wildcard.
• The keyword host as an abbreviation for source and
source-wildcard of source 0.0.0.0.
(Optional) The source-wildcard applies wildcard bits to the
source.
(Optional) Enter log to cause an informational logging message
about the packet that matches the entry to be sent to the console.
(Optional) Enter smartlog to send copies of denied or permitted
packets to a NetFlow collector.
Note Logging is supported only on ACLs attached to Layer 3
interfaces. Smart logging is supported only on ACLs
attached to Layer 2 interfaces.
Step 3
end Return to privileged EXEC mode.
Step 4
show access-lists [number | name] Show the access list configuration.
Step 5
copy running-config startup-config (Optional) Save your entries in the configuration file.
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