R3166-R3206-HP High-End Firewalls Access Control Configuration Guide-6PW101

• auto—Sorts ACL rules in depth-first order. Depth-first ordering ensures that any subset of a rule is

always matched before the rule. Table 1 lists the

sequence of tie breakers that depth-first ordering

uses to sort rules for each type of ACL.

Table 1 Sort ACL rules in depth-first order

ACL cate

uence of tie breakers

IPv4 basic ACL

1. VPN instance

2. More 0s in the source IP address wildcard (more 0s means a narrower IP

address range)

3. Smaller rule ID

IPv4 advanced ACL

1. VPN instance

2. Specific protocol type rather than IP (IP represents any protocol over IP)

3. More 0s in the source IP address wildcard mask

4. More 0s in the destination IP address wildcard

5. Narrower TCP/UDP service port number range

6. Smaller rule ID

Ethernet frame header ACL

1. More 1s in the source MAC address mask (more 1s means a smaller MAC

address)

2. More 1s in the destination MAC address mask

3. Smaller rule ID

NOTE:

wildcard mask, also called an inverse mask, is a 32-bit binary and represented in dotted decimal

notation. In contrast to a network mask, the 0 bits in a wildcard mask represent ‘do care’ bits, and the 1

bits represent ‘don’t care’ bits. If the 'do care' bits in an IP address are identical to the ‘do care’ bits in an

IP address criterion, the IP address matches the criterion. All ‘don’t care’ bits are i

nored. The 0s and 1s

in a wildcard mask can be noncontiguous. For example, 0.255.0.255 is a valid wildcard mask.

ACL rule numbering

NOTE:

The web interface does not support ACL numbering step configuration.

What is the ACL rule numbering step

If you do not assign an ID for the rule you are creating, the system automatically assigns it a rule ID. The

rule numbering step sets the increment by which the system automatically numbers rules. For example, the

default ACL rule numbering step is 5. If you do not assign IDs to rules you are creating, they are

numbered 0, 5, 10, 15, and so on. The wider the numbering step, the more rules you can insert between

two rules.

By introducing a gap between rules rather than contiguously numbering rules, you have the flexibility of

inserting rules in an ACL. This feature is important for a config order ACL, where ACL rules are matched

in ascending order of rule ID.

Automatic rule numbering and renumbering

The ID automatically assigned to an ACL rule takes the nearest higher multiple of the numbering step to

the current highest rule ID, starting with 0.