Generic Filter Rule; Figure 122 Executing An Ip Filter - ZyXEL Communications ADSL2+ Ethernet/USB Gateway 660RU-Tx Series User Manual

Prestige 660RU-Tx Series User's Guide

Figure 122 Executing an IP Filter

Packet
into IP Filter
Filter Active?
Yes
Apply SrcAddrMask
to Src Addr
Check Src
IP Addr
Matched
Apply DestAddrMask
to Dest Addr
Check Dest
IP Addr
Matched
Check
IP Protocol
Matched
Check Src &
Dest Port
Matched
More?
No
Action Matched
Drop
Drop Packet

22.4.2 Generic Filter Rule

This section shows you how to configure a generic filter rule. The purpose of generic rules is
to allow you to filter non-IP packets. For IP, it is generally easier to use the IP rules directly.
For generic rules, the Prestige treats a packet as a byte stream as opposed to an IP packet. You
specify the portion of the packet to check with the Offset (from 0) and the Length fields, both
in bytes. The Prestige 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 fields 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.
185
No
Not Matched
Not Matched
Not Matched
Not Matched
Yes
Check Next Rule
Check Next Rule
Forward
Check Next Rule
Action Not Matched
Drop Forward
Accept Packet
Chapter 22 Filter Configuration