Filtering cycles

The filtering process on the appliance has three cycles: the request cycle, the response cycle, and the embedded objects cycle. Only one of them can go on at a given moment.

The request cycle is performed for filtering requests that users of your network send to the web, the response cycle is for the responses received upon these requests from the web.

When embedded objects are sent with requests or responses, the embedded objects cycle is performed as an additional cycle of processing.

An embedded object could, for example, be a file sent with a request to upload a file and embedded in this file. The filtering process begins with the request cycle, filtering the request and checking the file that is requested for uploading. Then the embedded objects cycle is started for the embedded file.

Similarly, the response cycle and the embedded objects cycle are started one after another for a file that is sent in response from a web server and has another file embedded in it.

For every rule on the appliance, it is specified in which cycle it is processed. However, the cycle is not specified individually for a rule, but for the rule set that contains it.

A rule set can be processed in just one cycle or in a combination of cycles.