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Cisco ME 3800X and 3600X Switch Software Configuration Guide
OL-23400-01
Chapter 26 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.
Creating a Numbered Standard ACL
Beginning in privileged EXEC mode, follow these steps to create a numbered standard ACL:
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.
Note
When creating an ACL, remember that, by default, the end of the ACL contains an implicit deny
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.
Command
Purpose
Step 1
configure terminal
Enter global configuration mode.
Step 2
access-list access-list-number {deny | permit}
source [source-wildcard] [log]
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.
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.
