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Catalyst 2928 Switch Software Configuration Guide
OL-23389-01
Chapter 30 Configuring Network Security with ACLs
Configuring IPv4 ACLs
For an entry in a named IP ACL, use the
remark
access-list configuration command. To remove the
remark, use the
no
form of this command.
In this example, the Jones subnet is not allowed to use outbound Telnet:
Switch(config)#
ip access-list extended telnetting
Switch(config-ext-nacl)#
remark Do not allow Jones subnet to telnet out
Switch(config-ext-nacl)#
deny tcp host 171.69.2.88 any eq telnet
Applying an IPv4 ACL to a Terminal Line
You can use numbered ACLs to control access to one or more terminal lines. You cannot apply named
ACLs to lines. You must set identical restrictions on all the virtual terminal lines because a user can
attempt to connect to any of them.
For procedures for applying ACLs to interfaces, see the
“Applying an IPv4 ACL to a VLAN Interface”
Beginning in privileged EXEC mode, follow these steps to restrict incoming and outgoing connections
between a virtual terminal line and the addresses in an ACL:
To remove an ACL from a terminal line, use the
no access-class
access-list-number
{
in
|
out
} line
configuration command.
Applying an IPv4 ACL to a VLAN Interface
This section describes how to apply IPv4 ACLs to VLAN interfaces. Note these guidelines:
•
Apply an ACL to either inbound or outbound VLAN interfaces to filter packets that are intended for
the CPU, such as SNMP, Telnet, or web traffic. IPv4 ACLs applied to VLAN interfaces provide
switch management security by limiting access to a specific host in the network or to specific
applications (SNMP, Telnet, SSH, and so on). ACLs attached to VLAN interfaces do not impact the
hardware switching of packets on the VLAN.
•
When controlling access to a VLAN interface, you can use a named or numbered ACL.
Command
Purpose
Step 1
configure terminal
Enter global configuration mode.
Step 2
line
[
console
|
vty
]
line-number
Identify a specific line to configure, and enter in-line configuration mode.
•
console
—Specify the console terminal line. The console port is DCE.
•
vty
—Specify a virtual terminal for remote console access.
The
line-number
is the first line number in a contiguous group that you want
to configure when the line type is specified. The range is from 0 to 16.
Step 3
access-class
access-list-number
{
in
|
out
}
Restrict incoming and outgoing connections between a particular virtual
terminal line (into a device) and the addresses in an access list.
Step 4
end
Return to privileged EXEC mode.
Step 5
show running-config
Display the access list configuration.
Step 6
copy running-config startup-config
(Optional) Save your entries in the configuration file.
