ZyXEL 202H 91-003-194003B User Manual

P-202H Plus v2 User’s Guide

Chapter 25 Filter Configuration

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For generic rules, the ZyXEL Device treats a packet as a byte stream as opposed to an IP or 
IPX packet. You specify the portion of the packet to check with the Offset (from 0) and the 
Length fields, both in bytes. The ZyXEL Device applies the Mask (bit-wise ANDing) to the 
data portion before comparing the result against the Value to determine a match. The Mask 
and Value are specified in hexadecimal numbers. Note that it takes two hexadecimal digits to 
represent a byte, so if the length is 4, the value in either field will take 8 digits, for example, 
FFFFFFFF.

To configure a generic rule, select Generic Filter Rule in the Filter Type field in menu 
21.1.x.x and press [ENTER] to open Generic Filter Rule, as shown below.

Figure 145   Menu 21.1.4.1 Generic Filter Rule

The following table describes the fields in the Generic Filter Rule menu.

   Menu 21.1.4.1 - Generic Filter Rule

         Filter #: 4,1
         Filter Type= Generic Filter Rule
         Active= No
         Offset= 0
         Length= 0
         Mask= N/A
         Value= N/A
         More= No           Log= None
         Action Matched= Check Next Rule
         Action Not Matched= Check Next Rule

   Press ENTER to Confirm or ESC to Cancel:

Table 81   Menu 21.1.x.x Generic Filter Rule Menu Fields

Filter #

This is the filter set, filter rule co-ordinates, i.e., 2,3 refers to the 

second filter set and the third rule of that set.

Filter Type

Use [SPACE BAR] and then [ENTER] to select a rule type. 

Parameters displayed below each type will be different. TCP/IP filter 

rules are used to filter IP packets while generic filter rules allow 

filtering of non-IP packets.

Active

Select Yes to turn on the filter rule or No to turn it off.

Yes / No

Offset

Enter the starting byte of the data portion in the packet that you wish 

to compare. The range for this field is from 0 to 255.

0-255

Length

Enter the byte count of the data portion in the packet that you wish 

to compare. The range for this field is 0 to 8. 

0-8

Mask

Enter the mask (in Hexadecimal notation) to apply to the data 

portion before comparison.

Value

Enter the value (in Hexadecimal notation) to compare with the data 

portion.