Figure 33-8 Executing An Ip Filter; Generic Filter Rule - ZyXEL Communications Prestige 662HW Series User Manual

Prestige 662HW Series User's Guide
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?
Action Matched
Drop
Drop Packet

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.
33-8
No
Not Matched
Not Matched
Not Matched
Not Matched
Yes
No
Check Next Rule
Forward
Check Next Rule

Figure 33-8 Executing an IP Filter

Action Not Matched
Check Next Rule
Drop Forward
Accept Packet
Filter Configuration