SMC Networks 6128PL2, Management Manual

Page: 154 / 664

Configuring the Switch
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3
Access Control Lists
Access Control Lists (ACL) provide packet filtering for IP frames (based on address,
protocol, Layer 4 protocol port number or TCP control code) or any frames (based
on MAC address or Ethernet type). To filter incoming packets, first create an access
list, add the required rules, and then bind the list to a specific port.
Configuring Access Control Lists
An ACL is a sequential list of permit or deny conditions that apply to IP addresses,
MAC addresses, or other more specific criteria. This switch tests ingress or egress
packets against the conditions in an ACL one by one. A packet will be accepted as
soon as it matches a permit rule, or dropped as soon as it matches a deny rule. If no
rules match for a list of all permit rules, the packet is dropped; and if no rules match
for a list of all deny rules, the packet is accepted.
Command Usage
The following restrictions apply to ACLs:
• Each ACL can have up to 100 rules.
• However, due to resource restrictions, the average number of rules bound to the
ports should not exceed 20.
• When an ACL is bound to an interface as an egress filter, all entries in the ACL
must be deny rules. Otherwise, the bind operation will fail.
• The switch does not support the explicit “deny any any” rule for the egress IP ACL.
If these rules are included in ACL, and you attempt to bind the ACL to an interface
for egress checking, the bind operation will fail.
The order in which active ACLs are checked is as follows:
1. User-defined rules in the Egress IP ACL for egress ports.
2. User-defined rules in the Ingress IP ACL for ingress ports.
3. Explicit default rule (permit any any) in the ingress IP ACL for ingress ports.
4. If no explicit rule is matched, the implicit default is permit all.
Setting the ACL Name and Type
Use the ACL Configuration page to designate the name and type of an ACL.
Command Attributes
• Name – Name of the ACL. (Maximum length: 15 characters)
• Type – There are three filtering modes:
- Standard – IP ACL mode that filters packets based on the source IP address.
- Extended – IP ACL mode that filters packets based on source or destination IP
address, as well as protocol type and protocol port number.
- MAC – MAC ACL mode that filters packets based on the source or destination