ZyXEL Communications ZyXEL ZyWALL P1 - Manual (Page 106)

ZyWALL P1 User’s Guide
Chapter 7 Firewall Screens 105
3 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.
4 Does this rule conflict with any existing rules?
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.
7.3.3 Key Fields For Configuring Rules
7.3.3.1 Action
Should the action be to Block or Forward?
Note: “Block” means the firewall silently discards the packet.
7.3.3.2 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 7.8 on page 116 for more information on predefined services.
7.3.3.3 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?
7.3.3.4 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?
7.4 Connection Direction Examples
This section describes examples for firewall rules for connections going from LAN to WAN
and from WAN to LAN.
LAN to LAN/ZyWALL and WAN to WAN/ZyWALL rules apply to packets coming in on the
associated interface (LAN or WAN respectively). LAN to LAN/ZyWALL means policies for
LAN-to-ZyWALL (the policies for managing the ZyWALL 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/ZyWALL policy applyies in the same way to the WAN ports.