ZyXEL Communications P-2602HWLNI, User Manual, Page: 247 / 496

Chapter 15 Firewall Configuration
P-2602HWLNI User’s Guide
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2 Does this rule stop LAN users from accessing critical resources on the Internet? For
example, if IRC is blocked, are there users that require this service?
3 Is it possible to modify the rule to be more specific? For example, if IRC is blocked for
all users, will a rule that blocks just certain users be more effective?
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.
15.3.3 Key Fields For Configuring Rules
15.3.3.1 Action
Should the action be to Drop , Reject or Permit ?
"
“Drop” means the firewall silently discards the packet. “Reject” means the
firewall discards packets and sends an ICMP destination-unreachable
message to the sender.
15.3.3.2 Service
Select the service from the Service scrolling list box. If the service is not listed, it is necessary
to first define it. See Appendix E on page 475 for more information on predefined services.
15.3.3.3 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?
15.3.3.4 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?
15.4 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 and DMZ to DMZ/ Router rules apply 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.