ZyXEL Communications HS100/HS100W manual Configuring a Generic Filter Rule, Executing an IP Filter

HomeSafe User’s Guide

Packet

into IP Filter

Filter Active?	No
Yes
Apply SrcAddrMask
to Src Addr
Check Src	Not Matched
IP Addr
Matched
Apply DestAddrMask
to Dest Addr
Check Dest	Not Matched
IP Addr
Matched
Check	Not Matched
IP Protocol
Matched
Check Src &	Not Matched
Dest Port
Matched
More?	Yes
No		Action Not Matched
Action Matched	Check Next Rule
	Check Next Rule	Drop	Forward
Drop	Forward
Drop Packet	Check Next Rule		Accept Packet

Figure 27-7 Executing an IP Filter

27.2.3 Configuring a 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 HomeSafe 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 HomeSafe 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.

Filter Configuration 27-7