ZyXEL Communications Prestige 861H-G1, User Manual

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Prestige 861H User’s Guide
23-8 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 23-8 Executing an IP Filter
23.4.2 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.