ZyXEL Communications Parental Control Gateway HS100/HS100W - Manual (Page 274)

HomeSafe User’s Guide
Filter Configuration 27-11
Figure 27-11 Example Filter Rules Summary: Menu 21.1.3
After you’ve created the filter set, you must apply it.
Step 1. Enter 11 from the main menu to go to menu 11.
Step 2. Go to the Edit Filter Sets field, press [SPACE BAR] to select Yes and press
[ENTER].
Step 3. This brings you to menu 11.5. Apply a filter set (our example filter set 3) as shown in
Figure 27-14.
Step 4. Press [ENTER] to confirm after you enter the set numbers and to leave menu 11.5.
27.4 Filter Types and NAT
There are two classes of filter rules, Generic Filter (Device) rules and protocol filter (TCP/IP)
rules. Generic filter rules act on the raw data from/to LAN and WAN. Protocol filter rules act on
the IP packets. Generic and TCP/IP filter rules are discussed in more detail in the next section.
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 HomeSafe 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, or device filters are applied to the raw packets that appear
on the wire. They are applied at the point when the HomeSafe is receiving and sending the
packets; i.e. the interface. The interface can be an Ethernet port or any other hardware port. The
following diagram illustrates this.
Menu 21.1.3 - Filter Rules Summary
# A Type Filter Rules M m n
- - ---- --------------------------------------------------------------- - - -
1 Y IP Pr=6, SA=0.0.0.0, DA=0.0.0.0, DP=23 N D F
2 N
3 N
4 N
5 N
6 N
Enter Filter Rule Number (1-6) to Configure:
This shows you that you have
configured and activated (A = Y) a
TCP/IP filter rule (Type = IP, Pr = 6)
for destination telnet ports (DP =
23).
M = N means an action can be taken immediately.
The action is to drop the packet (m = D) if the
action is matched and to forward the packet
immediately (n = F) if the action is not matched no
matter whether there are more rules to be
checked (there aren’t in this example).