Web Gateway 7.1.5 Product Guide - McAfee

4
Rules and rule sets
Contents
Filtering controlled by rules
About rule elements
About rule sets
Rule configuration
Rule set configuration
List maintenance
Action and engine settings
Access restrictions
Filtering controlled by rules
Whenever the appliance takes a filtering action to ensure web security for your network, it is executed
according to a rule. The sections of this chapter explain how you can work with these rules. They
describe the filtering process they are used in, their elements, and the rule sets that contain them.
They also explain how to work with the lists and modules that rules rely on for retrieving filter
information.
About filtering
This section explains some basic concepts of the filtering process that goes on when the implemented
rules are processed on the appliance.
In this process, the appliance “filters” web traffic. It blocks some objects and lets others pass through,
like a tea sieve or strainer that catches the tea leaves and allows the liquid to flow through its
perforations.
So how does the appliance tell the tea leaves from the liquid? The tea strainer obviously uses dimension
as a key concept. If something is too big, it cannot pass through.
Similarly, the appliance uses all kinds of properties that web objects can have or that are related in
some way to web objects to make its filtering decisions.
Properties of filtered objects
Properties of web objects checked in the filtering process are, for example, “being virus-infected” or
“belonging to a URL category” or “having a particular IP address”.
The following can then be asked about these properties:
• For a given web object, what value does property p have?
• And: If this value is x, what action is required?
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