HP-UX IPFilter Version A.03.05.14 Administrator's Guide

Rules and Keywords
IPFilter Keywords
Chapter 2 27
NOTE If you do not specify any out rules, the implied default is pass out all.
If you do not specify any in rules, the implied default is pass in all.
quick: Optimizing IPFilter Rules Processing
HP-UX IPFilter behaves differently from other packet filters. Because it
processes the whole ruleset for each packet, there might be a
performance impact if your rules file is configured so that the most
applicable rules are in the first 10 of 100 rules.
You can use the quick keyword to control rule processing and reduce
performance impact on your IPFilter system. If IPFilter matches a
packet to a rule that contains quick, IPFilter immediately acts on that
rule without continuing to check the packet against the other rules in the
ruleset. For example, if you configure the following ruleset:
block in quick all
pass in all
IPFilter matches all packets to the first rule, block in quick all and
blocks the packet. Because quick is used, IPFilter does not consider the
other rule in the ruleset.
on: Filtering by Network Interfaces
You can use the on keyword to control traffic to and from your system
based on network interfaces.
Your system can have interfaces to more than one network. Every packet
the system receives comes in on a network interface; every packet the
system transmits goes out on a network interface.
For example, your machine has two interfaces, lan0 and lan1, and you
do not want packets coming in on the lan0 interface. You add the
following rules:
block in quick on lan0 all
pass in all
The on keyword means that network traffic is coming in on the named
interface, lan0. If a packet comes in on lan0, the first rule blocks it. If a
packet comes in on lan1, the first rule does not match. The second rule
matches and the packet is passed.