3 key fields for configuring rules, 1 action, 2 service – ZyXEL Communications 802.11g ADSL 2+ 4-Port Security Gateway HW-D Series User Manual
Page 183: 3 source address, 4 destination address, 4 connection direction
P-662H/HW-D Series User’s Guide
Chapter 11 Firewall Configuration
183
4 Does a rule that allows Internet users access to resources on the LAN create a security
vulnerability? For example, if FTP ports (TCP 20, 21) are allowed from the Internet to the
LAN, Internet users may be able to connect to computers with running FTP servers.
5 Does this rule conflict with any existing rules?
6 Once these questions have been answered, adding rules is simply a matter of plugging the
information into the correct fields in the web configurator screens.
11.3.3 Key Fields For Configuring Rules
11.3.3.1 Action
Should the action be to Drop, Reject or Permit?
Note: “Drop” means the firewall silently discards the packet. “Reject” means the
firewall discards packets and sends an ICMP destination-unreachable
message to the sender.
11.3.3.2 Service
Select the service from the Service scrolling list box. If the service is not listed, it is necessary
to first define it. See
for more information on predefined services.
11.3.3.3 Source Address
What is the connection’s source address; is it on the LAN or WAN? Is it a single IP, a range of
IPs or a subnet?
11.3.3.4 Destination Address
What is the connection’s destination address; is it on the LAN or WAN? Is it a single IP, a
range of IPs or a subnet?
11.4 Connection Direction
This section describes examples for firewall rules for connections going from LAN to WAN
and from WAN to LAN. Rules for the DMZ work in a similar fashion.
LAN to LAN/ Router, WAN to WAN/ Router and DMZ to DMZ/Router rules applies to
packets coming in on the associated interface (LAN, WAN, or DMZ respectively). LAN to
LAN/ Router means policies for LAN-to-ZyXEL Device (the policies for managing the
ZyXEL Device through the LAN interface) and policies for LAN-to-LAN (the policies that
control routing between two subnets on the LAN). Similarly, WAN to WAN/ Router and
DMZ to DMZ/ Router polices apply in the same way to the WAN and DMZ ports.