Chapter 17: Access Control List Configuration Guide
236
DIGITAL GIGAswitch/Router User Reference Manual
ACL Basics
An ACL consists of one or more
rules
describing a particular type of IP or IPX traffic.
ACLs can be simple, consisting of only one rule, or complicated with many rules. Each
rule tells the GSR to either permit or deny packets that match selection criteria specified in
the rule.
Each ACL is identified by a name. The name can be a meaningful string, such as
denyftp
or
noweb
or it can be a number such as
100
or
101
.
For example, the following ACL has a rule that permits all IP packets from subnet
10.2.0.0/16 to go through the GSR:
Defining Selection Criteria in ACL Rules
Selection criteria in the rule describe characteristics about a packet. In the example above,
the selection criteria are IP packets from 10.2.0.0/16.
The selection criteria you can specify in an ACL rule depends on the type of ACL you are
creating. For IP, TCP, and UDP ACLs, the following selection criteria can be specified:
•
Source IP address
•
Destination IP address
•
Source port number
•
Destination port number
•
Type of Service (TOS)
For IPX ACLs, the following selection criteria can be specified:
•
Source network address
•
Destination network address
•
Source IPX socket
•
Destination IPX socket
acl 101 permit ip 10.2.0.0/16
