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Chapter 28
Configuring Network Security with 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.
Creating a Numbered Standard ACL
Beginning in privileged EXEC mode, follow these steps to create a numbered standard ACL:
Command
Step 1
configure terminal
Step 2
access-list access-list-number {deny | permit}
source [source-wildcard] [log]
Step 3
end
Step 4
show access-lists [number | name]
Step 5
copy running-config startup-config
Use the no access-list access-list-number global configuration command to delete the entire ACL. You
cannot delete individual ACEs from numbered access lists.
When creating an ACL, remember that, by default, the end of the ACL contains an implicit deny
Note
statement for all packets that it did not find a match for before reaching the end. With standard access
lists, if you omit the mask from an associated IP host address ACL specification, 0.0.0.0 is assumed to
be the mask.
78-17058-01
Purpose
Enter global configuration mode.
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.
Return to privileged EXEC mode.
Show the access list configuration.
(Optional) Save your entries in the configuration file.
Cisco ME 3400 Ethernet Access Switch Software Configuration Guide
Configuring IPv4 ACLs
28-9
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