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Catalyst 2950 Desktop Switch Software Configuration Guide
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Chapter 25 Con figuring Ne two rk Sec urity with ACLs
Configuring ACLs
This exampl e shows how to crea te a standard ACL to deny access to IP hos t 171.69.1 98.102 , permit
access to any others, and display the results.
Switch (config)# access-list 2 deny host 171.69.198.102
Switch (config)# access-list 2 permit any
Switch(config)# end
Switch# show access-lists
Standard IP access list 2
deny 171.69.198.102
permit any

Creating a Numbered Extended ACL

Although stan dard ACLs use only source addresses f or matching, you can use an extended ACL source
and destin ation a ddresses for matching operati ons and op tional pro tocol type informa tion fo r finer
granularity of control. Some protocols also have specific parameters and keywords that apply to that
protocol .
These IP protocols are supported on physical in te rfaces (protocol keywords are in parenthese s in bold):
Intern et Protocol (ip), Transmission Con trol Pr otocol (tcp), o r User D atagr am Pr otoc ol ( udp).
Supporte d parame ters can be gro uped int o these cat egories:
TCP
UDP
Table 25-3 lists the possible filtering parameters for ACEs for each protocol type.
For more details about the specific keywords relative to each protocol, refer to the Cisco IP and IP
Routing Com mand R eference for I OS R e lease 12. 1.
Table 25-3 Filtering Parameter ACEs Supported by Different IP Protocols
Filtering Parameter1
1. X in a protocol column means support for the filtering parameter.
TCP UDP
Layer 3 Parameters:
IP type of service (ToS) byte2
2. No support for type of service (ToS) minimize monetary cost bit.
––
Differentiated Services Code Point (DSCP) X X
IP source addre ss X X
IP destinati on address X X
Fragments ––
TCP or UDP X X
Layer 4 Parameters
Source por t operat or X X
Source por t X X
Destina tion port operator X X
Destinati on port X X
TCP fl ag ––