ZyXEL Communications Prestige 662HW Series, User Manual

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Prestige 662HW Series User’s Guide
33-8 Filter Configuration
Packet
into IP Filter
Matched
Matched
Yes
Action Matched
Action Not Matched
More?
No
Filter Active?
Check
IP Protocol
Drop
Drop Packet Accept Packet
Drop Forward
Check Next Rule
Check Next Rule
Check Next Rule
Forward
Not Matched
Yes
No
Check Src
IP Addr
Apply SrcAddrMask
to Src Addr
Matched
Check Dest
IP Addr
Apply DestAddrMask
to Dest Addr
Not Matched
Not Matched
Check Src &
Dest Port
Matched
Not Matched
Figure 33-8 Executing an IP Filter
33.4.2 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.