ZyXEL Communications Prestige 661H Series, User Manual

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Prestige 661H/HW Series User’s Guide
Chapter 12 Firewall Configuration 146
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.
12.3.3 Key Fields For Configuring Rules
12.3.3.1 Action
Should the action be to Block or Forward ? “Block” means the firewall silently discards the
packet.
12.3.3.2 Service
Select the service from the Service scrolling list box. If the service is not listed, it is necessary
to first define it. See Section 12.10 on page 158 for more information on predefined services.
12.3.3.3 Source Address
What is the connection’s source address; is it on the LAN, WAN? Is it a single IP, a range of
IPs or a subnet?
12.3.3.4 Destination Address
What is the connection’s destination address; is it on the LAN, WAN? Is it a single IP, a range
of IPs or a subnet?
12.4 Connection Direction
This section describes examples for firewall rules for connections going from LAN to WAN
and from WAN to LAN.
LAN to LAN/ Router, WAN to WAN/ Router rules apply to packets coming in on the
associated interface (LAN, WAN respectively). LAN to LAN/ Router means policies for
LAN-to-Prestige (the policies for managing the Prestige 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 polices apply in the same way to the WAN ports.
12.4.1 LAN to WAN Rules
The default rule for LAN to WAN traffic is that all users on the LAN are allowed non-
restricted access to the WAN. When you configure a LAN to WAN rule, you in essence want
to limit some or all users from accessing certain services on the WAN. WAN to LAN Rules