Packet Filter Technical Reference; Filter Types And Nat; Figure 106 Protocol And Generic Filter Sets - ZyXEL Communications P-660HN User Manual

Table 65 Security > Packet Filter > Edit (Generic Filter) > Edit Rule (continued)
LABEL
Value
More
Log
Action Match
Action Not Match
Back
Apply
Cancel

11.3 Packet Filter Technical Reference

This section provides some technical background information about the topics covered in this
chapter.

11.3.1 Filter Types and NAT

There are two classes of filter rules, generic filter rules and protocol filter rules. Generic filter
rules act on the raw data from/to LAN and WAN. Protocol filter rules act on the IP packets.
When NAT (Network Address Translation) is enabled, the inside IP address and port number
are replaced on a connection-by-connection basis, which makes it impossible to know the
exact address and port on the wire. Therefore, the ZyXEL Device applies the protocol filters to
the "native" IP address and port number before NAT for outgoing packets and after NAT for
incoming packets. On the other hand, the generic filters are applied to the raw packets that
appear on the wire. They are applied at the point when the ZyXEL Device is receiving and
sending the packets; that is the interface. The interface can be an Ethernet port or any other
hardware port. The following diagram illustrates this.

Figure 106 Protocol and Generic Filter Sets

Route
P-660HN-Fx User's Guide
DESCRIPTION
Enter the value (in hexadecimal notation) to compare with the data portion.
Select Yes to pass a matching packet to the next filter rule before an action
is taken.
Select No to act upon the packet according to the action fields.
Select a logging option from the following:
None – No packets will be logged.
Match - Only packets that match the rule parameters will be logged.
Not Match - Only packets that do not match the rule parameters will be
logged.
Both – All packets will be logged.
Select the action for a matching packet.
Options are Check Next Rule, Forward and Drop.
Select the action for a packet not matching the rule.
Options are Check Next Rule, Forward and Drop.
Click this to return to the previous screen without saving.
Click this to save your changes.
Click this to restore your previously saved settings.
Protocol
NAT
Filters
Chapter 11 Packet Filter
Incoming
Generic
Filters
Outgoing
Interface
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