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Catalyst2950 and Catalyst2955 Switch Software Configuration Guide
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Chapter29 Configuring Network Security with ACLs
Configuring ACLs
•All ACEs in an ACL must have the same user -defined m ask. Ho weve r , A CEs can ha ve d ifferent rules
that use the same mask. On a given interface, only one type of user-defined mask is allo wed, b ut you
can apply any number of system-defined masks. For more information on system-defined masks, see
the “Understanding Access Control Parameters” section on page 29-4.
This example shows the same mask in an ACL:
Switch (config)# ip access-list extended acl2
Switch (config-ext-nacl)# permit tcp 10.1.1.1 0.0.0.0 any eq 80
Switch (config-ext-nacl)# permit tcp 20.1.1.1 0.0.0.0 any eq 23
In this example, the first ACE permits all the TCP packets coming from host 10.1.1.1 with a
destination TCP port number of 80. The second ACE permits all TCP packet s com ing fro m host
20.1.1.1 with a destination TCP port number of 23. Both the ACEs use the same mask; t he refore, a
switch supports this ACL.
•When you apply an ACL to a physical interface, some keywords are not supported and certain mask
restrictions apply to the ACLs. See the “Creating a Numbered Standard ACL” section on page 29-9
and the “Creating a Numbered Extended ACL” section on page29-10 for creating these ACLs.
Note You can also apply ACLs to a management interface without the abov e limitations. For information, refer
to the “Configuring IP Services” section of the Cisco IOS IP and IP Routing Configuration Guide, Cisco
IOS Release 12.1 and the Cisco IOS IP and IP Routing Command Reference, Cisco IOS Re lease 12 .1 .
Configuring ACLs
This section includes these top ics :
•“Unsupported Features” section on page 29-7
•“Creating Standard and Extended IP ACLs” section on page 29-7
•“Creating Named MAC Extended ACLs” section on page 29-18
•“Creating MAC Access Groups” section on page29-19
Configuring ACLs on a Layer 2 interface is the same as configuring ACLs on Cisco routers. The process
is briefly described here. For more detailed information about co nfigurin g rou ter ACLs, refer to the
“Configuring IP Services” chapter in the Cisco IP and IP Routing Configuration Guide, Cisco IOS
Release12.1. For detailed information about the commands, refer to the Cisco IOS IP and IP Routing
Command Reference, Cisco IOS Release 12.1. For a list of Cisco IOS feature s n ot su ppo rte d on the
switch, see the “Unsupported Features” section on page 29-7.